208279795 GIA s Colored Stone Essential s Reference Guide

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Reference Guide

ESSENTIAL C

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Reference Guide

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© 1999 The Gemological Institute of America All rights reserved: Protected under the Berne Convention. No part of this work may be copied, reproduced, transferred, or transmitted in any form or by any means whatsoever without the express written permission of GIA. Printed in the United States. Reprinted 2005

Table of Contents Introduction

1

Agate

2

Alexandrite

4

Almandite

6

Amber

8

Amethyst

10

Aquamarine

12

Bloodstone

14

Carnelian

16

Cat’s-Eye

18

Black Chalcedony

20

Chalcedony

22

Citrine

26

Coral

28

Demantoid

32

Emerald

34

Hematite

38

Hessonite

40

Iolite

42

Ivory

44

Jade (Jadeite)

46

Jade (Nephrite)

50

Kunzite

54

Lapis Lazuli

56

Malachite

58

Malaya Garnet

60

Moonstone

62

Morganite

64

Onyx and Sardonyx

66

Opal

68

Pearl and Cultured Pearl

72

Peridot

76

Pyrope

78

Rhodolite

80

Rose Quartz

82

Ruby

84

Sapphire

88

Shell

92

Smoky Quartz

96

Spessartite

98

Spinel

100

Star Ruby

102

Star Sapphire

106

Tanzanite

110

Tiger’s-eye

112

Topaz

114

Tortoise Shell

118

Tourmaline

120

Tsavorite

124

Turquoise

126

Zircon

130

Introduction For centuries, artists and poets have used images of colored stones to express love, passion, and power. People in every era and from all walks of life have adorned themselves with the dramatic, radiant grace of colored stone jewelry. This volume, The Essential Colored Stone Reference Guide (The Reference Guide for short), is written in lively, understandable language, with stunning illustrations and an easy, look-it-up format. Convenient organization makes it easy to put The Reference Guide to work for you. Entries are listed alphabetically by common name. Applicable species, variety, and group names are listed below the heading. You can refer to the Table of Contents if you want to go directly to a specific listing. Each entry provides clear, practical information that you can use to enrich your sales presentations. For example, a “Care and Cleaning” chart lists common cleaning methods and the relative safety of each method for that particular gem. Common synthetics, treatments, and imitations are listed as appropriate, too. Another feature of each entry is the list of alternative gems at the end of each section. This will be useful to you when, for example, you’re talking with a customer who loves purple, but isn’t sure she wants an amethyst. Besides practical information, some gem entries include interesting lore. For example, did you know that amber is sometimes called “Gold of the North,” or that emerald was one of Cleopatra’s favorite gems? There’s also a list of the places considered sources of each gem. These bits of information can enhance your presentation and make the gem more interesting to your customer. The Reference Guide covers gems you’re likely to see in jewelry stores, catalogs, and other retail settings. But the world of colored stones is vast and varied, and even a guide like this can’t possi bly include every gem or every property of a given gem. GIA also offers the more advanced—and more technical— Gem Reference Guide, which discusses the gems covered here as well as lesswell-known gems, and offers more scientific detail on each gem. The Essential Colored Stone Reference Guide is your key to the product knowledge you need to sell color with style and confidence. When new colored stone jewelry appears in your inventory, look it up in the guide. And by all means, use The Reference Guide to help you answer customer questions. You’ll find that with its beautiful photographs and friendly format, it’s a powerful sales tool.

©1999

by GIA. All rights reserved.

1

Agate Agate/Chalcedony

Carved agate

Agate is a fine-grained chalcedony quartz and one of the first gem materials known. Its history goes all the way back to the ancient Egyptians, who first used it for adornment more than 3,000 years ago. Ancient cultures used it in amulets and talismans. They believed that it provided the wearer with a bold heart and pleasant dreams. Roman artisans carved seals from it. Nineteenth century Victorians used it to create beautiful cameos. The characteristic that sets agate apart from other chalcedonies is its appearance: It boasts dramatic curved or angular stripes, or bands of color. These distinctive markings vary widely in color and translucence. The patterns in some agates look like moss, ferns, and trees—even entire landscapes. Others have simple striped patterns of two or more colors. Besides cameos, modern cutting styles that make the most of agate’s unique appearance include cabochons, beads, and carvings. Fire agate is a relative newcomer to the agate family, discovered in the 1940s. Its mineral layers cause light interference and give it a shimmering iridescence against its brown bodycolor.

Sources Brazil India Madagascar Mexico United States Uruguay

Hardness & Toughness

2

Hardness

61/2 to 7 on Mohs scale

Toughness

Good

Varieties Eye agate, orbicular agate

Banded in concentric rings

Landscape agate

Chalcedony with colored patterns resembling a landscape

Fire agate

Iridescent inner layers

Dendritic agate, scenic agate

Colorless or white, translucent, with markings resembling trees, ferns, moss, or landscapes Landscape agate

Iris agate

Semitransparent to translucent, with iridescent colors

Stability Environmental Factor

Reaction

Heat

Color may change

Light

Stable

Chemicals

Attacked by hydrofluoric acid; nitric acid may attack dye

Treatments Treatment

Description

Purpose

Dyeing

Gray South Improves color, American agate is improves banddyed with inoring ganic dye. Layers absorb dye differently depending on porosity.

Generally stable Common under normal conditions. May fade or be removed by chemicals.

Heating

Produces orange or orangy red color in yellow to brown agate

Permanent

Improves color

Stability

Prevalence Iris agate

Common

Care and Cleaning Type of Cleaning

Advisability

Steam cleaning

Not recommended

Ultrasonic cleaning

Not recommended

Warm, soapy water

Safe

Landscape agate

3

Alexandrite Alexandrite/Chrysoberyl

Alexandrite is a rare chrysoberyl variety with chameleon-like qualities. Its color is a lovely green in daylight or fluorescent light, but it changes to brownish or purplish red in the incandescent light from a lamp or candle flame. Alexandrite’s dramatic color change is sometimes described as “emerald by day, ruby by night.” Other gems also change color in response to a change in light source, but this gem’s transformation is so striking that the phenomenon itself is often called “the alexandrite effect.” Abundant alexandrite deposits were first discovered in 1830, in Russia’s Ural Mountains. Those first alexandrites were of very fine quality, and dis played vivid hues and dramatic color changes. The gem was named after the young Czar Alexander II, and it caught the country’s attention because its red and green colors mirrored the Imperial Russian flag. The spectacular Ural Mountain deposits didn’t last forever, and now most alexandrite comes from Sri Lanka, East Africa, and Brazil. The newer deposits contain some fine-quality stones, but many possess less precise color change and muddier hues than the nineteenth century Russian alexandrites. You’ll still find some of the famed Ural Mountain alexandrites in estate jewelry. They remain the quality standard for this phenomenal gemstone. Because of its scarcity, especially in larger sizes, alexandrite is a relatively expensive member of the chrysoberyl family. It shares its designation as a June birthstone with cultured pearl and moonstone.

Sources Brazil East Africa Russia Sri Lanka 4

Hardness & Toughness Hardness

81/2 on Mohs scale

Toughness

Excellent


Reaction

Heat

Stable

Light

Stable

Chemicals

None

Alexandrites in incandescent light


Advisability

Ultrasonic cleaning

Usually safe

Steam cleaning

Usually safe

Warm, soapy water

Safe

Alexandrites in fluorescent light

Imitations Synthetic color-change sapphire Synthetic color-change spinel

Synthetics Flux Czochralski

Alternatives Color-change garnet Color-change sapphire

5

Almandite Almandite/Garnet

Almandite is probably one of the most familiar of the closely related species that make up the garnet group. It’s a fairly common red garnet, with a color range from orangy red through red to reddish purple. Almandite was named for Alabanda, an ancient Asian town and an active gemstone trading and fashioning center. Ancient Romans often fashioned almandite garnets as thin, hollowed cabochons to bring out the intensity of their color. Other species in the garnet group come in a variety of hues, from browns and oranges to vibrant greens. As far back as 3100 BC, Egyptians along the Nile worked garnet into beads and inlays. Noah is said to have recognized garnet’s inner fire and used it as a lamp on the bow of the ark. Garnets of all species, including almandite, are considered January birthstones.

Sources Brazil India Madagascar Pakistan Sri Lanka United States

6


7 to 71/2 on Mohs scale

Toughness

Fair to good


Reaction

Heat

Abrupt temperature changes likely to cause fracturing

Light

Stable

Chemicals

None, except concentrated hydrofluoric acid


Advisability

Ultrasonic cleaning

Usually safe

Steam cleaning

Never

Warm, soapy water

Safe

Imitations Garnet-and-glass doublet

Alternatives Hessonite garnet Malaya garnet Pyrope garnet Rhodolite garnet Ruby Spessartite garnet Spinel Tourmaline

7

Amber

Amber belongs to the category of organic gems—the products of living organisms and biological processes. Amber formed millions of years ago, when sap from ancient trees hardened and fossilized. Stone Age people discovered these golden jewels along the shores of the Baltic Sea, and they became perhaps the earliest and most consistently popular ornamental gems. Scientists and collectors treasure amber that contains suspended animal or plant fragments: Fossilized bits of once-living things that were trapped in the hardening amber millions of years ago, creating a fascinating time capsule. Some types of amber are found in the ground. Other types have been freed and carried by tides and end up on beaches or near-shore areas. The Baltic coast bordering Germany, Poland, and Russia is still a source of amber, which is sometimes called “gold of the North.” Amber’s warm luster is featured in beads, carvings, pendants, and cabochon rings, as well as decorative items like cups, bowls, snuff boxes, and umbrella handles. Amber’s colors range from whites, yellows, and oranges to reds and browns. Clear material is preferred in the US, cloudy in Europe and North Africa. Heating cloudy amber in oil clarifies it. Heat treatment can also produce disk-like stress fractures and create an attractive product called sun-spangled amber.

Sources Dominican Republic Germany Mexico Poland Russia

8

Currently the major source



Toughness

Poor


Reaction

Heat

Burns at low temperatures

Light

May darken with age

Chemicals

Attacked by acids, caustics, alcohol, gasoline

Amber pendant showing sun spangles


Purpose

Stability

Prevalence

Detection

Heating in oil

Clarifies cloudy amber

Stable

Occasional

May be detectable

Heating

Lightens color

Stable

Occasional

Undetectable

Heating (sometimes with oil)

Produces sun spangles

Stable

Common

May be detectable

Dyeing

Darkens color

May fade

Occasional

May be detectable


Advisability

Steam cleaning

Never

Ultrasonic cleaning

Never

Warm, soapy water

Safe, but hard brushes may scratch

Imitations Ambroid (reconstructed or pressed amber) Copal (a natural resin, younger than amber) Plastic Yellow glass

Close-up of spider trapped in amber

Close-up of insect trapped in amber

9

Amethyst Amethyst/Quartz

Amethyst has been the most prized member of the quartz family for centuries. Early Greek legends, and its wine-purple color, associated amethyst with Bacchus, the god of wine. Other legends led to beliefs that amethyst gems kept their wearers clear-headed and quick-witted in battle and in their business affairs. It’s no wonder that fine amethyst adorns the fingers of bishops and the coronation regalia of British royalty. Russia was once the main source of amethyst, but near the turn of the twentieth century, new deposits were discovered in South America. After that, it became more widely available, but no less treasured. Amethyst comes in a range of sizes, and the color selection ranges from palest lilac to rich purple. Experts consider African amethyst’s royal purple with reddish overtones to be the gem’s finest color. A closely related quartz variety called ametrine contains a striking mixture of two contrasting quartzes— purple amethyst and yellow citrine. Ametrine deposits are found in Brazil and Bolivia. Amethyst is the birthstone for February.

Sources Brazil

Major source

India Namibia Sri Lanka United States Uruguay Zambia


10

Hardness

7 on Mohs scale

Toughness

Good


Reaction

Heat

Abrupt temperature change may fracture stone, can alter color

Light

Some amethyst may fade

Chemicals

Damaged by hydrofluoric acid, ammonium fluoride, alkalies


Purpose

Stability

Prevalence

Detection

Heating

Lightens color or produces citrine or green quartz

Excellent

Occasional

Undetectable


Advisability

Steam cleaning

Not recommended

Ultrasonic cleaning

Usually safe

Warm, soapy water

Safe

Imitations Glass Purple synthetic corundum Assembled stone (synthetic spinel triplet) Contemporary amethyst and diamond pendant

Synthetics Hydrothermal

Alternatives Iolite Rhodolite garnet Sapphire Spinel Tanzanite Topaz Carved amethyst

Tourmaline

Ametrine

11

Aquamarine Aquamarine/Beryl

Aquamarine’s cool blue hues are reflected in its name, which comes from the Latin for “sea water.” Medieval sages prescribed water touched by aquamarine for a host of ills, including those affecting the eyes and lungs. They promised the virtues of insight and foresight to the gem’s wearers. Aquamarine crystals can grow to huge sizes, and are usually blessed with excellent clarity. Gem bodycolors range from greenish blue to blue-green in light tones. Usually, the color is more intense in larger stones, but some aquamarine from Africa displays deeper blues in faceted stones of less than 5 cts. Brazil supplies the most aquamarine to the modern market. Like emerald, aquamarine is a member of the beryl species. The gem is March’s birthstone.

Sources Australia Brazil

Major source

China Kenya Madagascar Mozambique Nigeria

Known for intense color in smaller sizes (under 5 cts.)

Pakistan United States Zambia


12

Hardness


Toughness

Good


Reaction

Heat

Exposure to heat not recommended

Light

Stable

Chemicals

Attacked by hydrofluoric acid

A 32.10-ct. heart-shaped aquamarine from Brazil


Purpose

Stability

Prevalence

Detection

Heating

Removes yellow, resulting in purer blue color

Very good

Routine

Undetectable


Advisability

Ultrasonic cleaning

Usually safe, unless stone contains feathers or liquid inclusions

Steam cleaning

Usually safe, unless stone contains feathers or liquid inclusions

Warm, soapy water

Safe

Imitations Glass Synthetic spinel

Alternatives Blue topaz

Flower brooch featuring aquamarine

Sapphire Spinel Tanzanite Tourmaline

Aquamarine crystal from Afghanistan weighing over 100 cts.

13

Bloodstone Bloodstone/Chalcedony

Bloodstone is an opaque to semitranslucent variety of chalcedony. Its bold coloring—dark green flecked with red—has intrigued people for centuries. The ancient Greeks named it heliotrope (“sun-turner”) because they observed that it flashed scarlet when they lowered it into water and pointed it toward the sun. Many people thought it colored water red for the same reason. Citizens of Medieval and Renaissance Europe honored bloodstone as a talisman that stirred passion, stopped bleeding, and brought healing. Rich men in the time of King Solomon prized the gem for use in their seal rings, and it’s still set in men’s jewelry today. Bloodstone is also popular in Christian jewelry because its distinctive pattern reminded early Christians of the blood of Christ at the foot of the cross.

Bloodstone is the alternate birthstone for March.

Sources Australia Brazil China India United States

14



Toughness

Good

Stability Environmental Factor Heat

Reaction Color may change

Light

Stable

Chemicals



Advisability

Ultrasonic cleaning

Not recommended

Steam cleaning

Not recommended

Warm, soapy water

Safe

15

Carnelian Carnelian/Chalcedony

Carnelian is a semitransparent to translucent variety of chalcedony. Gem specialists believe it was named after the kornel cherry, which grows in the same warm shades as the gem: Yellowish orange to orangy red to brownish orange. It’s often fashioned into beads or cameos to show off its color. Ancient civilizations believed that carnelian transformed poor or timid speakers into eloquent ones. Carnelian’s history began in India, where it was mined as early as the fourth century BC.

Sources Brazil India Uruguay



Toughness

Good

Stability

16

Environmental Factor

Reaction

Heat

Color may change

Light

Stable

Chemicals



Purpose

Stability

Prevalence

Detection

Heating

Improves color

Stable

Common

Undetectable


Advisability

Ultrasonic cleaning

Usually safe

Steam cleaning

Usually safe

Warm, soapy water

Safe

Imitations Glass Plastic

Alternatives Amber Fire opal Jade Sard chalcedony

Carnelian intaglio

Carnelian intaglio ring

Roman carnelian intaglio from the first century BC

17

Cat’s-Eye Cat’s-Eye/Chrysoberyl

This gem, with its band of reflected light across the middle, has always reminded observers of the eye of a cat. The cat’s-eye effect, also called chatoyancy, is caused by parallel needle-like inclusions within the stone. The gem was once known as cymophane—Greek for “waving light.” In some cultures, its distinctive appearance made it the preferred treatment for all sorts of eye ailments. Chatoyancy appears in other gemstones, but fine-quality cat’s-eye chrysoberyl sets the standard. It’s also the most valuable cat’s-eye stone. It’s durable as well as attractive, which makes it popular in men’s rings, cufflinks, and tie tacks. The cabochon cut brings out its cat’s-eye effect to best advantage. Cat’s-eye chrysoberyl ranges from brown to greenish yellow. The finest quality specimens boast a golden color, with bands that span the entire length of the gem. The bands themselves are distinct, silvery-white, and straight. The chatoyant band in cat’s-eyes will appear to blink when you hold the stone between two light sources, then rotate it. As you turn the stone, the eye splits into two bands that move apart, then back together. This effect is called “opening and closing.” Cat’s-eyes display another impressive effect, called milk and honey. With the light positioned perpendicular to the chatoyant band, the side nearest the light shows the stone’s original bodycolor while the other side has a milky appearance.

18

Sources Brazil East Africa Sri Lanka


81/2 on Mohs scale

Toughness

Excellent to good


Reaction

Heat

Stable

Light

Stable

Chemicals

None

72.68-ct. cat's-eye chrysoberyl cabochon with a 317.7-ct piece of rough from Brazil


Advisability

Ultrasonic cleaning

Usually safe

Steam cleaning

Usually safe

Warm, soapy water

Safe

Imitations Cat’s-eye glass

Alternatives Cat’s-eye quartz Cat’s-eye tourmaline

Cat’s-eye chrysoberyl set in art deco-style platinum ring with diamonds

Tiger’s-eye quartz

Cat’s-eye chrysoberyl mounted in art deco pin

19

Black Chalcedony

Natural black chalcedony is extremely rare. The jewelry industry commonly calls dyed black chalcedony, which is more common, “black onyx.” This always-stylish gem was prominent in the Art Deco jewelry of the 1920s and 1930s. Jewelry designers of the time often set it in platinum with diamonds, or with the colorless quartz variety known as rock crystal. Because “basic black” is always in style, so is black chalcedony. It has the added advantages of good durability, low cost, and availability in an almost unlimited range of sizes. It’s one of the most popular gems for beads, cabochons, tablets, inlays, and carvings. You’ll often find this stone in men’s jewelry. Black chalcedony is also commonly used as a backing for opal doublets and triplets. In doublets, pieces of opal too thin to use alone are often cemented to a tablet of black chalcedony. This dramatizes the opal’s play of color and gives strength to the assembled stone. A triplet requires the addition of a protective top made of rock crystal quartz or some other hard, colorless material.

Sources Brazil

Gray chalcedony, later dyed black


20

Hardness


Toughness

Good

Stability Environmental Factor Heat

Reaction Color may change

Light

Stable

Chemicals

Attacked by hydrofluoric acid; nitric acid may attack dye


Purpose

Stability

Boiling in a solution of sugar and water, then soaking in sulfuric acid. Usually described as “dyeing.”

Produces black color in gray chalcedony

Stable under normal conditions

Prevalence

Detection

Routine. Virtually all black chalcedony is dyed.

No tests. Treatment is assumed.


Advisability

Ultrasonic cleaning

Usually safe

Steam cleaning

Usually safe

Warm, soapy water

Safe


Alternatives Hematite Jadeite jade Nephrite jade Onyx

21

Chalcedony Chalcedony is one of the world’s oldest, most abundant, and most popular gems. It was named for the ancient Turkish seaport of Chalcedon (now called Kadikoy). Many cultures throughout history have used it for a variety of purposes. Many considered it a powerful talisman. In the third and fourth centuries, Greek sailors wore chalcedony amulets as protection against drowning. As late as the 1700s, many Europeans believed chalcedony would drive away ghosts and bad spirits. Chalcedony is fairly affordable, and it comes in an incredibly wide range of colors and patterns. These two factors make it very popular with gem and mineral collectors. In jewelry, you’ll see it most often as beads, cabochons, tablets, and carvings. Imaginative designers use chalcedony in some of the most cutting-edge creations available on the market. Mineralogists consider chalcedony a variety of quartz, but gemologists and gem professionals treat the two as separate species. The difference between them is that quartz occurs in large crystals, while the individual crystals that make up chalcedony are so small that it takes very high magnification to see them.

Sources See Agate, Bloodstone, Carnelian, and Onyx and Sardonyx for sources of those gems.

22

Australia

Chrysoprase

Brazil

Many varieties

Czech Republic

Chrysoprase

Germany

Jasper

Iceland

Milky chalcedony

India

Chrysoprase, milky chalcedony

Italy

Jasper

Mexico

Chrysocolla-in-chalcedony

Russia

Jasper, milky chalcedony

Scotland

Jasper

United States

Amethystine chalcedony, chrysocolla-in-chalcedony, chrysoprase, jasper, milky chalcedony

Uruguay

Sard



Toughness

Good

Varieties Variety Name

Appearance and Comments

Agate

Translucent to opaque, with curved or angular color banding; also patterns such as “moss” and “landscape.” For additional information, see Agate.

Amethystine chalcedony

Semitranslucent to opaque purple. Often marketed as “purple agate” or under the trade name “damsonite.”

Bloodstone

Semitranslucent to opaque, dark green with red to brownish red spots. For additional information, see Bloodstone.

Carnelian

Semitransparent to translucent, yellow-orange to orangy red, often slightly brownish. For additional information, see Carnelian.


Translucent to semitranslucent, intense light blue or blue-green. Can resemble fine turquoise. One of the most valuable chalcedony varieties.

Chrysoprase

Semitransparent to translucent, light to medium yellowish green. The name comes from Greek words meaning “golden apple,” and is ethically used only for natural-color (not dyed) material.

Dendritic agate

Chalcedony with dark inclusions resembling tree branches.

Fire agate

Semitranslucent to opaque, with iridescent colors against a brown bodycolor.

Iris agate

Semitransparent to translucent, with iridescent colors (phenomenon best seen on thin slices in transmitted light)

Jasper

Opaque; any color or combination of colors except solid black or material known by another name (agate, black chalcedony, carnelian, and so forth). Opaque whitish jasper is often dyed blue to imitate lapis lazuli.


23

Milky chalcedony

Semitransparent to translucent, nearly colorless to white or light gray. Often sold as an alternative for moonstone.

Onyx

Translucent to opaque, with straight, parallel bands of different colors. For additional information, see Onyx and Sardonyx.

Sard

Semitransparent to translucent, dark brown, brownish orange, or brownish red (darker and less saturated color than carnelian).

Sardonyx

Onyx with sard colors alternating with either white or black. For additional information, see Onyx and Sardonyx.

Stability

Chrysoprase chalcedony

24


Reaction

Heat

Color may change, especially if dyed

Light

Stable

Chemicals

Attacked by hydrofluoric acid; nitric acid may attack dye in treated material


Purpose

Stability

Prevalence

Detection

Dyeing

Produces a wide variety of colors

Generally sta ble under normal conditions

Common

Some colors detectable by a trained gemologist or gemological laboratory.* Often assumed because of unnatural color.

* If there is any doubt, send the gem to a gemological laboratory for verification. Even then, some colors are not detectable.


Advisability

Ultrasonic cleaning

Usually safe

Steam cleaning

Usually safe

Warm, soapy water

Safe


Alternatives Amber Hematite Jadeite jade Lapis lazuli Malachite Moonstone Nephrite jade Rose quartz Shell Tiger’s-eye

Dendritic chalcedony

Turquoise

25

Citrine Citrine/Quartz

Citrine is one of the US birthstones for November (the other is topaz). It’s a quartz variety, and the top-selling transparent gem in the yellow to orange color range. Its name was derived from the Latin word citrus, meaning “citron” (a fruit closely related to the lemon). This gem combines a warm, attractive color with good wearability and a moderate price—an unbeatable combination for many customers. Citrine comes in an exceptionally wide range of sizes. The largest trans parent faceted gem on record (in terms of dimensions and volume) is a citrine. It measures 25.5 cm ˘ 14.1 cm ˘ 10.0 cm (9.9 in. ˘ 5.5 in. ˘ 3.9 in.), and weighs 19,548 cts. (3.9 kg/8.6 lb.). Jewelry-sized citrines are readily available in weights of up to 20 cts. and more. Most citrine is faceted in traditional rounds and fancy shapes, but you’ll also find it fashioned into more unusual cuts and carvings. Leading jewelry designers use citrine alone, in combination with diamonds, and in multicolored creations alongside gems with contrasting colors— amethyst, aquamarine, blue topaz, and others. Before the development of modern gemology, citrine was traditionally confused with topaz because of their similar colors.

Sources Bolivia Brazil Spain


26

Hardness

7 on Mohs scale

Toughness

Good


Reaction

Heat

High heat can cause color loss; sudden or extreme temperature change can cause fracturing

Light

Stable

Chemicals

Soluble in hydrofluoric acid and ammonium fluoride; very slightly soluble in alkalis 6.20-ct. citrine from Brazil


Purpose

Stability

Heating

Produces color— Permanent under changes normal condiamethyst to cittions rine

Prevalence

Detection

Routine. Most citrine is produced by heat treating amethyst.

Undetectable. Treatment is assumed.


Advisability

Ultrasonic cleaning

Usually safe

Steam cleaning

Not recommended

Warm, soapy water

Safe

Carved citrine

Imitations Glass Plastic Synthetic hydrothermal quartz Synthetic sapphire

Citrine Quartz from Brazil

Synthetic spinel

Alternatives Amber Carnelian Chrysoberyl Malaya garnet Sapphire Smoky quartz Spessartite garnet Topaz Tourmaline 27

Coral

For thousands of years, cultures around the world have prized coral as a gem and credited this product of the sea with magical powers. First century Romans used it to ward off evil and to impart wisdom. It’s still worn in modern-day Italy as protection against the “evil eye” and as a cure for sterility. There are two basic types of gem coral. One type comes in a variety of lighter shades: White, cream or pink, various shades of red or orange, and occasionally blue, purple, or light grayish violet (known as “lavender” in the trade). The other coral type is black, dark brown, or sometimes light brownish yellow (often called “golden”). All coral is composed of the remains of skeleton-like support structures that were built by colonies of tiny marine animals. These coral polyps, as they’re called, are close relatives of the more familiar coral reef builders. Coral jewelry, in the form of beads, cabochons, and especially small carvings and cameos, has been popular in Europe since Roman times. Its popularity is strong in both North and South America. At one time, Asian countries used coral more often for large carvings, but Western influences prompted increased production and popularity of coral jewelry in the twentieth century. World demand for coral jewelry remains high, even though a number of factors have combined to drastically reduce the supply of new material in recent decades. These factors include pollution, over-harvesting, and increasing national and international environmental protection efforts. For centuries, the most prized qualities of coral came from the Mediterranean Sea, along the coasts of Algeria, France, Italy, Morocco, Spain, and Tunisia. 28

Unfortunately, pollution and depletion have devastated these waters. Australia—another once-important source—now prohibits the export of all native coral. The state of Hawaii protects black “King’s” coral as an endangered species. All these factors limit modern supplies of coral, but the availability of high-quality older pieces guarantee it a permanent place in the antique market.

Sources Japan Malaysia Philippines


3 to 4 on Mohs scale

Toughness

Fair to good

Chimera bracelet bangle by Cartier (not signed) of carved coral set with diamonds in platinum


Reaction

Heat

Blackens or burns if exposed to the flame of a jeweler’s torch

Light

Generally stable; dyed material may eventually fade

Chemicals

Easily attacked by acids and other chemicals

Red coral

29


Purpose Deepens or changes color, usually to pink or red, but any color is possi ble

Stability Dye can be affected or removed by solvents, and can fade under prolonged exposure to strong light

Impregnation with epoxy resin or gluelike sustances

Fills and hides cavities and fractures

Bleaching in hydrogen peroxide solution

Produces “golden” color in black coral

Dyeing

Prevalence

Detection

Occasional

Might be detectable by a trained gemologist or gemological laboratory*

Stable under normal conditions, but can be damaged or destroyed by high heat and solvents

Common in low-quality material

Detectable by a trained gemologist or gemological laboratory

Stable

Common

Detectable by a trained gemologist or gemological laboratory

* If there is any doubt, send the gem to a gemological laboratory for verification.

30


Advisability

Ultrasonic cleaning

Risky

Steam cleaning

Never

Warm, soapy water

Safe


Alternatives Amber Carnelian Chalcedony Carved and rough coral

Cultured pearl Jadeite jade Nephrite jade Rose quartz Shell

Enamel and coral beads torsade necklace

Different types and colors of coral

31

Demantoid Demantoid/Andradite/Garnet

Demantoid means “diamond-like” in Dutch, the language of Renaissance diamond cutters. Its name reflects the fact that, while demantoid is much softer than diamond, its dispersion is higher, so its flashes of rainbow color are very noticeable, especially in lighter-colored stones. This lush green gem is a variety of andradite and a member of the garnet group. Demantoid displays intense color in the green to yellow-green range. Under the microscope, fine demantoid has another telltale signature: Its classic “horse-tails.” They are wisps of long, golden, fiber-like inclusions that radiate from a central point. Demantoid was discovered in Russia’s gem-rich Ural Mountains in 1868. Tiffany and Company’s chief gem buyer, George Kunz, fell in love with the newly discovered gem, and the company bought up all that they could get. Tiffany marketed it as an appealing emerald alternative. Even though it was rarely available in sizes larger than 2 cts., demantoid adorned much Victorian jewelry crafted between 1895 and 1915. The historic Russian source doesn’t yield much demantoid any more. In fact, the scarcity of fine-quality demantoid has made it a prized collector’s stone. Recent discoveries in Namibia, however, have increased the availability. Demantoid joins the rest of the garnet group as a January birthstone.

Sources Namibia Russia Zaire

32



Toughness

Fair to good


Reaction

Heat

Abrupt temperature changes likely to cause fracturing

Light

Stable

Chemicals


Close-up of the horsetail inclusion in a demantoid


Advisability

Ultrasonic cleaning

Usually safe, risky if contains liquid inclusions

Steam cleaning

Never

Warm, soapy water

Safe

Visible horsetail inclusion in a demantoid garnet

Imitations Colored CZ Colored YAG Garnet-and-glass doublet

Alternatives Emerald Green sapphire Green zircon Peridot Tourmaline Tsavorite garnet

33

Emerald Emerald/Beryl

Emerald’s lush green has soothed souls and excited imaginations since antiquity. Its name comes from the ancient Greek word for green, “smaragdus.” Rome’s Pliny the Elder described emerald in his Natural History, published in the first century AD: “…nothing greens greener” was his verdict. He described the use of emerald by early lapidaries, who “have no better method of restoring their eyes than by looking at the emerald, its soft, green color comforting and removing their weariness and lassitude.” Even today, the color green is known to relieve stress and eye strain. The first known emerald mines were in Egypt, dating from at least 330 BC into the 1700s. Cleopatra was known to have a passion for emerald, and used it in her royal adornments. Emeralds from what is now Colombia were part of the plunder when sixteenth-century Spanish explorers invaded the New World. The Indians had already been using emeralds in their jewelry and religious ceremonies for 500 years. The Spanish, who treasured gold and silver far more than gems, traded emeralds for precious metals. Their trades opened the eyes of European and Asian royalty to emerald’s majesty. Emerald is often mined and sold under peril—the natural resource Colombians cherish is also coveted by underworld drug traders. The availability of fine-quality emerald is limited, and emerald was plagued in the late 1990s by negative publicity about treatments commonly used to improve its clarity. Emerald is the most famous member of the beryl family. Legends gave it the power to make its wearer more intelligent and quick-witted. It was once also believed to cure diseases like cholera and malaria. Its color reflects new spring growth, which makes it the perfect choice of a birthstone for the month of May. It’s also the gemstone for twentieth and thirty-fifth wedding anniversaries.

34

Sources Afghanistan Brazil Colombia

One of the largest commercial producers: Fine Colombian emeralds are highly regarded for their excellent color

Pakistan Russia Zambia

A major commercial source: Zambian emeralds tend to have good clarity

Zimbabwe

The Sandawana Valley is a famous source



Toughness

Poor to good


Reaction

Heat

May cause fractures

Light

Fracture fillings may dry out or alter under intense light

Chemicals

Fracture fillings may be affected by any type of chemical, emerald itself is resistant to all acids except hydrofluoric

Emerald cross recovered from Nuestra Senora de Atocha Galleon

35


Description

Purpose

Stability

Prevalence

Fracture Filling

Filling surfacereaching fractures with colorless oils or resins. Simply called “oiling” in the trade when colorless oils are used.

Improves clarity, improves color

Not permanent

Routine

Dyeing

Adding colorant to the oils or resins used in the fracturefilling process

Improves emerald color, gives light-colored beryls an emerald green color

Not permanent

Rare

Coating

Covering a light-colored beryl with a green plastic

Creates an emerald imitation

Not permanent

Rare

Care and Cleaning Most emeralds have been fracture-filled. An emerald’s appearance may change over time due to the instability of its filling material. Depending upon their condition, emeralds may be retreated by an experienced professional.

36

Type of Cleaning

Advisability

Steam cleaning

Never

Ultrasonic cleaning

Never

Warm, soapy water

Usually safe. Avoid vigorous scrubbing

Imitations Green glass Synthetic spinel triplet

Synthetics Flux Hydrothermal

Alternatives Alexandrite Demantoid garnet Diopside Jadeite Peridot Sapphire Tourmaline Tsavorite garnet Zircon

Colombian rough and cut emeralds

37

Hematite

Hematite’s shiny metallic luster and dark gray to black color give it a special beauty and appeal that’s shared by few other stones. It’s inexpensive, and available in a wide range of sizes, so it’s a traditional favorite for men’s rings—especially when it’s engraved with a warrior ’s head or animal motif. It’s also widely used for pendants as well as bead necklaces and bracelets. Hematite has the highest density (weight-to-size ratio) of any commonly available natural gem. This gives hematite jewelry a weighty feel and an aura of value. Its high density has a down side for some wearers of hematite earrings, though: Large pendant and hoop styles are too heavy to wear comfortably for long periods. Hematite is composed of iron oxide, so it’s chemically the same as common rust. The name comes from the Greek word haima, which means “blood”—referring to the red color of the mineral in its powder form. Hematite’s name means, literally, “blood stone.” People in ancient mideastern cultures believed that hematite would ensure victory in lawsuits and favorable judgments from kings and others in authority. During Roman times, the gem was associated with Mars, god of war: It was believed to protect a warrior who rubbed it on his body. Native Americans also used powdered hematite as a pigment for war paint.

Sources England Norway Sweden United States

38


51/2 to 61/2 on Mohs scale

Toughness

Fair


Reaction

Heat

May become magnetic

Light

Stable

Chemicals

Soluble in hydrochloric acid


Advisability

Ultrasonic cleaning

Safe

Steam cleaning

Safe

Warm, soapy water

Safe

Imitations Imitation hematite—usually made mostly of compressed iron, and often stamped with an intaglio design. Once marketed as “hemetine,” but that trade name was ruled misleading by the FTC.

Alternatives Black chalcedony Cultured pearl Jadeite jade Nephrite jade

39

Hessonite Garnet/Grossularite/Hessonite

Hessonite is a variety of grossularite garnet. Its close relative, tsavorite, is also a grossularite variety. But hessonite’s warm brownish yellows, brownish oranges, and brownish reds make quite a contrast to tsavorite’s cool green. Because of hessonite’s color, as well as its historic connection with the spice-producing country of Sri Lanka, this garnet is also known as “cinnamon stone.”

Sources Brazil Canada Madagascar Mexico Sri Lanka Tanzania US


40

Hardness


Toughness

Fair to good


Reaction

Heat

Abrupt temperature change likely to cause fracturing

Light

Stable

Chemicals



Advisability

Ultrasonic cleaning

Usually safe, unless liquid inclusions are present

Steam cleaning

Never

Warm, soapy water

Safe

Alternatives Almandite Citrine Fire opal Sapphire Spessartite Topaz Zircon

41

Iolite

Iolite gets its name from the Greek word for violet, and like that flower, its cool shades range from light to dark blue and violet. It’s a transparent to translucent gem that’s strongly pleochroic. This means that it shows different colors from different viewing angles. From some angles, blue iolite can actually appear colorless. Other pleochroic colors include gray, violet, or yellow. This optical property allows the gem to act as a strong light polarizing filter, a feature that Viking navigators found useful. To locate the sun—and chart their position—on overcast days, they viewed the sky through a thin piece of iolite.

Sources Brazil India Madagascar Namibia Norway Sri Lanka Tanzania

42



Toughness

Fair


Reaction

Heat

Can be damaged

Light

Stable

Chemicals

Attacked by acids


Advisability

Ultrasonic cleaning

Risky

Steam cleaning

Risky

Warm, soapy water

Safe

Imitations Glass

Alternatives Blue topaz Sapphire Tanzanite

43

Ivory

Ivory is an organic material that has been part of human art and culture for thousands of years. It has always symbolized the strength, life force, and majesty of nature, and ivory objects served ceremonial, ornamental, and utilitarian purposes for most of the great civilizations. In Europe, archaeologists unearthed ivory carvings and artifacts that are as much as 30,000 years old. The Egyptians were crafting exquisite ivory ornaments by 8000 BC. Its easy workability and color palette—ranging from soft or radiant whites to warm light or golden brownish yellows—made ivory a prized medium for artisans, gem carvers, and jewelry designers. Today, ivory is one of the world’s most controversial gem materials. It comes from the tusks or teeth of certain mammals, and those mammals must die in order to yield their treasure. The most familiar ivory source is the ele phant. Others include the hippopotamus, narwhal, sperm whale, walrus, and warthog. Most are endangered species. International prohibitions exist (under the UN Convention on the International Trade in Endangered Species of Wild Flora and Fauna [CITES]) against trade in ivory. More than 100 nations are parties to CITES, and most of them have enacted laws to reinforce the ban. Beyond this, environmental and animal-rights activists militantly oppose commerce in ivory, and most consumers shun it as well. Despite all this, there’s still a strong market for ivory, which is now supplied almost exclusively by criminal means. A limited alternative to ivory is fossil ivory, which comes mostly from the remains of woolly mammoths that inhabited the northern hemisphere more than 10,000 years ago. Its main source is the Russian Siberian region. There’s also a legitimate collector’s market in antique ivory. Unfortunately, some dishonest traders use treatments to artificially “age” new ivory, thus avoiding the legal prohibitions.


44

Hardness

2⁄ to 2ﬂ on Mohs scale

Toughness

Fair


Reaction

Heat

Causes shrinkage, cracking, and discoloration

Light

Yellows with age

Chemicals

Attacked by many chemicals; softened by nitric and phosphoric acid

Ivory doctor’s doll


Stability

Prevalence

Detection

Stable

Common

Undetectable

Dyeing

Can impart any Stable color, but usually done to simulate the appearance of antique ivory

Common

Usually undetectable unless the color is unnatural in appearance

Heating

Stable Darkens the color to simulate the appearance of antique ivory

Undetermined

Usually undetectable

Bleaching

Purpose Lightens or removes stains


Advisability

Ultrasonic cleaning

Never

Steam cleaning

Never

Warm, soapy water

Safe


Alternatives Chalcedony Cultured pearl Jadeite jade Nephrite jade Shell

45

Jade [Jadeite]

There are two different gem minerals that are correctly called jade, and jadeite is one of them. (The other is nephrite.) Jadeite comes in a wide range of attractive colors: Many shades of green, yellow, and reddish orange, plus white, gray, black, brown and lavender (which often refers to light purple or light grayish violet). The coloration is often streaked or mottled, giving jadeite gemstones an interesting visual texture that carvers can use to create imaginative and intriguing effects. The finest quality jadeite—almost transparent with a vibrant emeraldgreen color—is known as “Imperial jade.” The royal court of China once had a standing order for all available material of this kind, and it’s one of the world’s most expensive gems. Other highly valued jade varieties include “kingfisher jade,” with a green color that’s only slightly less vivid than Imperial; “apple jade,” which is an intense yellowish green; and “moss-in-snow jade,” which is translucent white with bright green veining, patches, or spots. The most outstanding examples of these are almost always bought and sold in the Asian market. The Maya and the Aztecs prized jadeite from Central America. They used it for medicinal purposes as well as for jewelry, ornaments, and religious artifacts. The name jade comes from the Spanish expression piedra de ijada—literally “stone of the pain in the side.” Early Spanish explorers named it after they saw natives holding pieces of the stone to their sides to cure or relieve various aches and pains. It was in China—where the gem-carving tradition was already thousands of years old—that jadeite reached its peak as an important artistic medium. The first jadeite reached China from Burma (now known as Myanmar) in the late 1700s, and late eighteenth and

46

early nineteenth century carvers created masterpieces that are still unsur passed in concept, design, and technical execution. Jadeite is a favorite medium for lapidary artists around the world. This is especially true in China, where jade carving is still a national art form. It’s a popular material for beads, cabochons, bangle bracelets, and small carvings. Because of its exceptional strength and toughness, it’s one of the few gems that can be used to make hololiths—bracelets or rings carved entirely from a single piece of stone, with no supporting metalwork or mounting. Jadeite symbolizes prosperity, success, and good luck. It’s one of the topselling gems in Asia, but its versatile beauty and cultural associations have also earned it an important place in the global gem and jewelry market.

Various colors of jadeite.

Sources Guatemala Myanmar (Burma)

Major source of finest quality material

Russia United States



Toughness

Exceptional


Reaction

Heat

Damaged by a jeweler’s torch

Light

Stable

Chemicals

Slightly affected by warm acids

Lavender jadeite

47


Purpose

Stability

Prevalence

Detection

Dyeing (Referred to as “C jade”)

To add color (usually green or lavender) in white or lightcolored material

Fair to good. May fade with time

Common

Detectable by a trained gemologist or gemological laboratory*

Impregnation with paraffin wax

Hides fractures and improves polish appearance

Fair. Heat will destroy the treatment

Common


Bleaching and impregnation with plastic-type polymer resin. (A two-step process.) (Referred to as “B jade”)

Improves color; fills and hides fractures and cavities; improves polish appearance

Stable under normal conditions. High heat can damage or destroy the polymer

Common

Sometimes detectable by a trained gemologist. Definite proof usually requires advanced testing by a gemological laboratory*

Heating

Produces brown or reddish color in some material

Stable

Unknown

Undetectable


Jadeite and diamond brooch.

48


Advisability

Ultrasonic cleaning

Safe except for wax-impregnated material

Steam cleaning

Safe except for wax-impregnated material

Warm, soapy water

Safe


Synthetics Synthetic jadeite has been produced on a limited basis. Identification requires advanced testing. (If there is any doubt, send the gem to a gemological laboratory for verification.)

Alternatives Agate Amber

Jadeite carving

Black chalcedony Bloodstone Carnelian Chrysoprase chalcedony Malachite Nephrite jade Onyx Rose Quartz Shell Turquoise

49

Jade [Nephrite]

Nephrite jade has its cultural roots in the smoke-dimmed caves and huts that sheltered prehistoric humans. In China, Europe, and elsewhere around the world, Stone Age workers shaped this toughest of minerals into weapons, tools, ornaments, and ritual objects. Their carvings invoked the powers of heaven and earth and mystic forces of life and death. The ancient relationship between this gemstone and humanity persisted into modern times among native societies in New Zealand and parts of North America. In China it evolved into an artistic tradition that has flourished for more than 3,000 years. Nephrite is one of the two distinct minerals accepted as jade in the international gem and jewelry industry. (Jadeite is the other.) It ranges from translucent to opaque and can be light to dark green, yellow, brown, black, gray, or white. Its colors tend to be more muted than jadeite’s, and they’re often mottled or streaked. Its name comes from Latin words meaning “kidney stone”—a reference to the medicinal use of jadeite (with which nephrite was long confused) by Native Americans. Generally inexpensive, extremely wearable, and available in all sizes, nephrite is often used in jewelry for beads, cabochons, bangle-type bracelets, and carvings. The Chinese associate it with clarity of mind and purity of spirit. Some of the ancient symbolic motifs still used in modern jade carvings (both nephrite and jadeite) include: Bat—happiness Butterfly—long life Dragon—power, prosperity, and goodness Peach—immortality Pi (flat circular disk with a hole in the center)—heaven

50

Sources Canada China New Zealand Russia Taiwan United States



Toughness

Exceptional (the toughest known gem) Nephrite carving


Reaction

Heat

Damaged by a jeweler’s torch

Light

Stable

Chemicals

Slightly affected by warm acids

51


Purpose

Stability

Prevalence

Detection

Dyeing

Produces or improves color (usually green) in light-colored material

Variable, depending on the type of dye

Occasional


Impregnation with paraffin wax

Hides fractures and improves polish appearance

Fair. High heat will destroy the treatment

Common


Heating

Lightens color of Stable dark green material. Also darkens or “ages” white, yellow, or brown material

Unknown

Undetectable


Care and Cleaning

52

Type of Cleaning

Advisability

Ultrasonic cleaning

Safe except for wax-impregnated material.

Steam cleaning

Safe except for wax-impregnated material.

Warm, soapy water

Safe


Alternatives Agate Amber Black chalcedony Bloodstone Carnelian Chrysoprase chalcedony Hematite Jadeite jade Malachite Onyx Rose quartz Shell Turquoise

53

Kunzite Kunzite/Spodumene

George Frederick Kunz (1856-1932) was a pioneer gemologist and longtime buyer for Tiffany and Company. He was also a world-recognized expert on—and avid promoter of—American gemstones. In 1902, he identified a new gem-quality variety of the mineral spodumene in San Diego County, California. The new gem was named kunzite in his honor. This transparent stone’s light and delicate—but often bright—“rose” pink to bluish purple “lilac” color has endeared it to gem lovers and connoisseurs, especially in the US and Japan. The most valued kunzite colors are the more intense pinks and bluish purples, but the l ighter pinks are the most common. Kunzite is very popular with customers looking for gems in soft pastel colors. The supply of fine-quality kunzite is limited, but various faceted fancy shapes are usually available in sizes as large as 50 cts. The gem has poor toughness due to cleavage, and its attractive color can fade with exposure to bright light. Because of these factors, kunzite is a gem that requires special care, but many consider the extra care worthwhile because of its beauty.

Sources Afghanistan Brazil Madagascar United States


54

Hardness


Toughness

Poor because of cleavage


Reaction

Heat

High heat can cause color loss; sudden temperature change can cause breaks

Light

Bright light causes the color to fade

Chemicals

Very slowly attacked by concentrated hydrofluoric acid


Purpose

Stability

Prevalence

Detection

Irradiation

Produces kunzite from colorless or light-colored spodumene

Color fades in bright light light (as does untreated material)

Unknown

Undetectable


Advisability

Ultrasoniccleaning

Never

Steam cleaning

Never

Warm, soapy water

Safe

Imitations Glass Synthetic sapphire Synthetic spinel

Alternatives Amethyst Morganite Rhodolite garnet Rose quartz Sapphire Spinel Topaz Tourmaline

Necklace designed by Paloma Picasso, featuring large kunzite with diamonds and cultured pearls set in 18K gold

55

Lapis Lazuli

Lapis lazuli belongs to a small category of gems called “rocks” because it’s an aggregate aggregate of several different different minerals. (A mineral is a natural inorganic material with a specific—and unique—chemical composition and crystal structure). It’s often simply called “lapis” in the trade. Lapis is typically opaque, and its colors are medium to dark greenish “navy” blue, pure “royal” blue, or violetish “midnight” blue. Depending on its source, it sometimes shows white calcite veining, which lowers its value, or golden-looking flecks of the mineral pyrite. The pyrite spangles nestled in the blue bodycolor—like golden stars in a summer sky—produce a unique visual appeal. Lapis has been mined in Afghanistan for more than 6,000 years. It was treasured by the ancient civilizations of Mesopotamia, Egypt, China, Greece, and Rome. Its Latin name literally means “blue stone.” Lapis was considered an emblem of chastity and a cure for sadness. It was also thought to offer protection from evil and ensure the help of angels. The supply of lapis is plentiful in today’s jewelry market. Large stones are readily available, and it’s a popular gem material for beads, cabochons, tablets, and carvings. Afghan lapis has always been known for its fine quality and color purity, while lapis mined in Chile often shows less-desirable white veining. Lapis was dropped from the official US birthstone list in the 1950s, but for many years it was one of the gems for December. You might suggest it as an alternative for customers who were born in that month.

Sources Afghanistan—Finest Afghanistan—F inest quality Chile Russia


56

Hardness


Toughness

Fair


Reaction

Heat

High heat can induce an undesirable green color, or cause complete color loss

Light

Stable

Chemicals

Decomposed slowly by hydrochloric acid; discolored by cyanide solution


Purpose

Stability

Prevalence

Detection

Dyeing

Improves color and hides white veining

Fair. Some dyes fade or are affected by solvents

Common


Coating or impregnation with oil, paraffin, or plastic

Improves color and polish appearance; also seals any dye

Fair. Treatment (especially oil and paraffin) can be damaged or destroyed by heat and chemicals

Common




Advisability

Ultrasonic cleaning

Risky

Steam cleaning

Never

Warm, soapy water

Safe


Alternatives

Suite of high-quality lapis lazuli from Afghanistan

Chalcedony Sodalite

57

Malachite

Malachite is an opaque gem with a strong bluish green to green color. It typically shows curved or circular banding (in varying shades of green) that gives it a distinctive beauty. (A closely related gem material, azurmalachite, combines malachite green with the dark blue of the mineral azurite in attractive bands and patterns.) Malachite has a long history as a gem. One of its main components, and the cause of its color, is copper. It was found along with that metal by early civilizations as they emerged from the Stone Age. The Egyptians used malachite for jewelry and other ornamental purposes as early as 4000 Bc. In the Middle Ages (from about 500 to 1500 AD) people in Europe often hung malachite on cradles to assure peaceful sleep for their children and protect them from witchcraft. People wore pieces with eyeshaped markings as amulets to ward off the “evil eye.” Modern jewelry uses for malachite include beads, cabochons, tablets, inlays, and carvings. Its high density gives malachite jewelry such as bead necklaces a weighty feeling that enhances customers’ sense of its value. Because malachite is relatively soft, has poor toughness, and can be attacked by many chemicals, it’s considered an extra-care gem. With proper handling, however, malachite can provide years of pleasure for its wearer.

Sources Australia Russia United States Zaire


58

Hardness


Toughness

Poor


Reaction

Heat

High heat can cause discoloration and damage

Light

Stable

Chemicals

Attacked by acids


Purpose

Stability

Prevalence

Detection

Impregnation with paraffin or epoxy resin

Intensifies color, improves polish appearance, and hides small cracks

Fair. Treatment can be damaged or destroyed by heat and chemicals

Unknown




Advisability

Ultrasonic cleaning

Never

Steam cleaning

Never

Warm, soapy water

Safe


Synthetics

Suite of malachite

Synthetic malachite has been produced on a limited basis. Identification requires advanced testing. (If there is any doubt, send the gem to a gemological laboratory for verification.)

Alternatives Agate (dyed green) Jadeite jade Nephrite jade Turquoise

59

Malaya Garnet

Malaya (also spelled malaia) garnet is a relatively new member of the garnet group. Specimens of it first appeared in the 1960s, mixed in with parcels of rhodolite garnets from the Umba River Valley of East Africa. At first, buyers rejected the unfamiliar gem material, so local miners and dealers gave it a Swahili name that literally translates “out of the family.” Tests eventually proved malaya garnet to be a chemical mixture of two garnets: pyrope and spessartite. The gem’s lively color—light to dark pinkish, reddish, or yellowish orange—conquered buyer resistance, and during the 1980s it gained a small but strong market, particularly in the US. Malaya is one of the more expensive garnets. It’s usually available in various fancy shapes up to about 10 cts. Along with the other garnets, it’s a US birthstone for January. In Europe, malaya is known as umbalite, after the region that remains the gem’s only source.

Sources Kenya Tanzania


60

Hardness


Toughness

Fair to good


Reaction

Heat

Sudden temperature change can cause fracturing

Light

Stable

Chemicals

Slightly attacked by hydrofluoric acid


Advisability

Ultrasonic cleaning

Usually safe

Steam cleaning

Never

Warm, soapy water

Safe

Color-change 8.51-ct. malaya garnet under fluorescent light

Color-change 8.51-ct. malaya garnet under incandescent light


Alternatives Almandite Carnelian Citrine Sapphire Spessartite garnet Spinel

Color-change malaya garnets in fluorescent light

Topaz Tourmaline Zircon Color-change malaya garnets in incandescent light

61

Moonstone Moonstone/Orthoclase/Feldspar

Faceted moonstone with blue adularescence

According to Hindu mythology, moonstone is made of solidified moonbeams. Many other cultures also associate this gem with moonlight, and it’s easy to see why. Its internal structure scatters the light that hits it and creates a phenomenon known as adularescence. The visual effect is reminiscent of the full moon shining through a veil of high, thin clouds. Legends say that moonstone brings good luck. Many believed that you could see the future if you held a moonstone in your mouth during a full moon. Moonstone ranges from semitransparent to opaque. You’ll most often find it in cabochons and carvings, set in rings and pendants. It’s also popular in bead necklaces and bracelets. It’s usually colorless, white, or light bluish gray, with white or blue adularescence. Other colors include light green, yellow, brown, and sometimes gray to black. The market supply is normally steady in sizes up to about 25 cts., with larger stones available in limited quantities. Along with alexandrite and cultured pearl, moonstone is one of the US birthstones for June.

Sources India Myanmar (Burma) Sri Lanka


62

Hardness


Toughness

Poor because of cleavage


Reaction

Heat

High heat or sudden temperature change can cause breaks

Light

Stable

Chemicals



Advisability

Ultrasonic cleaning

Never

Steam cleaning

Never

Warm, soapy water

Safe

Carved moonstone and diamond pendant


Alternatives Milky chalcedony

63

Morganite Morganite/Beryl

In 1911, a transparent gem discovered on the African island of Madagascar was hailed as an exciting new alternative to kunzite and pink tourmaline. The rose pink to lilac gem was named in honor of wealthy banker and gem connoisseur John Pierpont Morgan. Morgan was an avid customer of Tiffany’s, and the jewelry store enthusiastically promoted the gem. Eventually, Madagascar’s morganite deposits declined and Brazil became the gem’s top producer. Although the gem’s finest color is a deep magenta, most morganites on the market are a pale pink. Many Brazilian morganites emerge from the mines sporting an attractive peach (orange pink) hue that’s appealing to some buyers. But producers usually heat treat gems of this hue to arrive at a pink shade that’s preferred in the marketplace. Morganite is a variety of beryl, which makes it a relative of emerald and aquamarine. The gem’s beauty and limited availability make it a favorite of collectors.

Sources Afghanistan Brazil Madagascar US


64

Hardness


Toughness

Good


Reaction

Heat

Pinkish orange may fade to pink; may fracture if liquid inclusions present

Light

Stable

Chemicals

Resistant to all acids except hydrofluoric


Purpose

Stability

Prevalence

Detection

Heating

Improves pink color by removing orange tint

Stable, except at temperatures over 400°C

Unknown

Undetectable


Advisability

Ultrasonic cleaning

Risky if highly included (rare)

Steam cleaning

Risky if highly included (rare)

Warm, soapy water

Safe

Alternatives Kunzite Pink tourmaline Rose quartz Sapphire Spinel Topaz

65

Onyx and Sardonyx Onyx/Chalcedony and Sardonyx/Chalcedony

Onyx and sardonyx are both chalcedony varieties characterized by straight, parallel bands of different colors. In onyx, the bands are usually black and white. In sardonyx, dark brown, brownish orange, or brownish red alternate with either white or black. Since Greek and Roman times, both varieties have provided gem carvers with ideal materials for cameos and intaglios. The color banding allows the creation of carved designs that contrast dramatically with their backgrounds. Inexpensive, plentiful, and available in large sizes, onyx and sardonyx are also traditionally popular for beads, cabochons, and tablets. In Europe, sardonyx once symbolized the humility of the saints and the virtue of spiritual living. Sardonyx is accepted as one of the US birthstones for August. (The other is peridot.)

Sources Brazil Madagascar United States Uruguay


66

Hardness


Toughness

Good

Stability Environmental factor

Reaction

Heat

Color may change

Light

Stable

Chemicals



Advisability

Ultrasonic cleaning

Usually safe

Steam cleaning

Usually safe

Warm, soapy water

Safe Sardonyx cameo


Alternatives Agate Carnelian Jadeite jade Nephrite jade Shell

Black and white onyx cameo set in gold and surrounded by pearls

67

Opal

Opal is the world’s most popular phenomenal gem. Many cultures have credited opal with supernatural origins and powers. Arabic legends say it falls from the heavens in flashes of lightning. The ancient Greeks believed opals gave their owners the gift of prophecy and guarded them from disease. Europeans have long considered the gem a symbol of hope, purity, and truth. Opal is one of the US birthstones for October (along with tourmaline). Some people think it’s unlucky for anyone born in another month to wear an opal. But that particular superstition comes from a novel written in the 1800s ( Anne of Geierstein by Sir Walter Scott) and not from ancient belief or experience. In fact, throughout most of history, opal has been regarded as the luckiest and most magical of all gems because it can show all colors. Once, it was thought to have the power to preserve the life and color of blond hair. Although experts divide gem opals into many different categories, four of the main types are: • White opal—translucent to semitranslucent with play-of-color against a white or light gray bodycolor • Black opal—translucent to opaque with play-ofcolor against a black or other dark bodycolor • Fire opal—transparent to translucent with brown, yellow, orange, or red bodycolor. This material— which often doesn’t show play-of-color—is also known as “Mexican opal,” “gold opal,” or “sun opal” • Boulder opal — translucent to opaque with play-ofcolor against a light to dark background. Host-rock fragments, or matrix, are part of the finished gem The market supply of fine black opal is extremely limited, but white and fire opals are generally available in a wide range of sizes. You’ll usually see black or white opals fashioned as cabochons and set in rings, pendants, pins, or earrings. Fire opals are used in the same kinds of jewelry, but they’re often faceted. All three types occasionally appear as beads and carvings. 68

Pieces of white or black opal that are too thin to use alone often become part of opal doublets or triplets. In these assembled stones, a sliver of opal is cemented—usually with black adhesive that dramatizes the play-of-color—to a backing such as chalcedony, glass, or plastic. A doublet consists of two pieces (the opal and the backing), while a triplet also has a protective top made of rock crystal quartz or colorless glass.

Explaining Play-of-color Play-of-color occurs because opal is made up of sub-microscopic spheres stacked in a grid-like pattern—like layers of Ping-Pong balls in a box. This structure breaks up light into spectral colors. The colors you see depend on the sizes of the spheres. Those approximately 0.1 micron (one tenmillionth of a meter) in diameter produce violet. Spheres about 0.2 microns in size produce red. Those in between produce intermediate hues. Common trade terms for play-of-color patterns include: • Pinfire or pinpoint—small, close-set patches of color • Harlequin or mosaic—broad, angular, close-set patches of color • Flame—sweeping reddish bands or streaks that shoot across the stone • Peacock—mainly blue and green

Sources Australia

Black and white opal

Brazil

White opal

Mexico

Fire opal

Blue opal pendant set in platinum with diamonds



Toughness

Very poor to fair

Fire opal

69


Reaction

Heat

High heat or sudden temperature change can cause fracturing

Light

Generally stable, but heat from intense light can cause fracturing (known as “crazing”)

Chemicals

Attacked by hydrofluoric acid and caustic alkalis

Warn buyers that loss of moisture, and crazing, can result from storage in airtight containers such as safe deposit boxes.


Purpose

Impregnation with oil, wax, or plastic

Stability

Prevalence

Detection

Improves play-of- Fair to poor for color and prevents oil or wax; excelor disguises frac- lent for plastic turing. Black plastic also creates the appearance of black opal

Common

Oil and wax treatments are detectable by a trained gemologist or gemological laboratory. Advanced laboratory testing is almost always required for plastic*

Soaking in dye, silver nitrate, or sugar and acid (known as “sugar treatment”)

Creates or Poor to good improves play-ofcolor and simulates the appearance of black opal

Common


Smoke impregnation

Creates or improves play-ofcolor and simulates the appearance of black opal

Fair to poor. Common Treatment is shallow, and abrades or chips away easily



70


Advisability

Ultrasonic cleaning

Never

Steam cleaning

Never

Warm, soapy water

Safe


Synthetics Available in a variety of colors

Alternatives No gem duplicates opal’s unique combination of color and phenomenon. As alternatives, you might suggest stones with similar bodycolors, or those that show other special optical effects. Fire agate Iris agate

71

Pearl and Cultured Pearl Perhaps the best-loved gems of all time, pearls—and their modern counter parts, cultured pearls—occur in a wide variety of colors. The most familiar colors are white and cream (light yellowish brown). Black, gray, and silver are also relatively common, but the palette of pearl colors extends to every hue. The bodycolor is often modified by additional colors called overtones, which are typically pink (called rosé), green, purple, or blue. And some pearls show the iridescent phenomenon known as orient. Pearls are treasures from the Earth’s streams, rivers, lakes, seas, and oceans, and they’ve always embodied the mystery, power, and life-sustaining nature of water. The spherical shape of some pearls also led many cultures to associate this gem with the moon. In ancient China, pearls were believed to guarantee protection from fire and fire-breathing dragons. In Europe, they symbolized modesty, chastity, and purity. Cultured pearls are popular for bead necklaces and bracelets, or mounted in solitaires, pairs, or clusters for use in earrings, rings, and pendants. Larger pearls with unusual shapes are favorites with creative jewelry designers. Pearl—cultured or natural—is a US birthstone for June, together with alexandrite and moonstone.

Natural and Cultured Pearls Natural pearls are organic gems that form in the bodies of certain mollusks, usually around a microscopic irritant and always without human help of any kind. They’re com posed mostly of concentric layers of nacre, which is made of the same basic material as mother-of-pearl—the inside layer of certain shells. Natural pearls were once more prevalent around the world—and prized by almost all cultures. They virtually disappeared from the mainstream jewelry market in the twentieth century due to pollution, over-fishing, and economic factors. Now normally available only through antique or estate dealers and auctions, fine natural pearls can command very high prices. The growth of cultured pearls requires human intervention and care. The mollusks themselves are raised specifically for culturing. To begin the process, skilled technicians insert one or more nuclei (usually shell beads or pieces of flesh from other mollusks) into each mollusk. These nuclei act as irritants and trigger the secretion of nacre. Workers tend the mollusks until the cultured pearls are harvested. This usually happens about 18 months, but 72

occasionally up to 3 years, after nucleation. Besides human intervention, another big difference between natural and many cultured pearls is that the bead nucleus accounts for most of the volume and weight of the cultured product. The first steps toward pearl culturing occurred hundreds of years ago in China, and Japanese pioneers successfully produced whole cultured pearls around the beginning of the twentieth century. These became commercially important in the 1920s (about the same time natural pearl production began to drop). From the 1930s through the 1980s, pearl culturing diversified and spread to various countries around the world. A trained gemologist can often identify cultured pearls—particularly in strands, necklaces, or bracelets—with a reasonably high degree of certainty. Positive identification of natural pearls requires advanced laboratory testing. If there is any doubt, send the gem to a gemological laboratory for verification.

FTC Guides on Pearls The US FTC Guides include several sections dealing with representations concerning natural, cultured, and imitation pearls. Some of the most important points are:

A pair of earrings with 2.22-ct. t.w. hot reddish pink spinels, spessartite garnets, and cultured pearl drops

• It’s unfair or deceptive to use the term “pearl” alone or the term “natural” (or anything similar) for cultured pearls or imitations • It’s unfair or deceptive to use terms such as “cultured,” “synthetic,” or anything similar for imitation pearls • It’s unfair or deceptive to use the term “Oriental pearl” for anything other than natural pearls from the Persian Gulf • It’s unfair or deceptive to use geographic terms like “South Sea” for cultured pearls from other sources • It’s unfair or deceptive to use the term “pearl” or “cultured pearl” for specimens of inferior appearance or quality

Cultured Pearl Types and Related Products • Akoya—the type of cultured pearl most familiar to many jewelry customers. The typical size range is 6 mm to 8 mm, but you might see akoya cultured pearls as small as 2 mm or as large as 11 mm. Most have a white to cream bodycolor. Other natural colors include yellow, gray, and blue. Japan and China both produce saltwater akoya cultured pearls. • South Sea—Australia, Indonesia, and the Philippines are leading sources of these saltwater cultured pearls. Myanmar (Burma) and Thailand are also important producers. South Sea cultured pearls usually range from about 8 mm to 18 mm in size. The most common bodycolors are white, cream, and golden (dark brownish yellow), but you’ll see them in other colors, too. • Tahitian—Cultivated primarily around the islands of French Polynesia (the most familiar of which is Tahiti), these saltwater cultured pearls usually range from white to black. Other colors include dark metallic 73

greens and purples. The usual size is about 8 mm to 17 mm, although larger pearls exist in limited quantities. • Freshwater—Pearls cultured in streams, rivers, and lakes. They’re produced in a wide range of sizes, shapes, and colors. China and the US are the leading sources. • Keshi (Japanese for “poppyseed”)—Pearls that form (without being intentionally nucleated) in mollusks undergoing pearl cultivation. • Blister pearls—Cultured or natural pearls that form over a solid core inside a freshwater or saltwater mollusk’s shell. The side that faces the shell is flat and lacks nacre. • Mabé—An assembled product consisting of a cultured blister pearl dome cemented to a backing made from mother-of-pearl shell. After harvesting, the nucleus is removed and the hollow interior is usually filled with a material such as epoxy resin.


21/2 to 4 on Mohs scale (very soft and easily scratched or abraded)

Toughness

Usually good, but variable due to aging, dehydration, and sometimes excessive bleaching during initial processing


Reaction

Heat

High heat can burn cultured pearls or cause discoloration, splitting, or cracking

Light

Generally stable, but heat from intense light can cause dehydration and nacre cracking

Chemicals

Attacked by many chemicals and all acids; hair spray, perfume, cosmetics, and even acid perspiration can damage nacre

Harry Winston black cultured pearl and diamond cufflinks

74


Purpose

Stability

Prevalence

Detection

Bleaching

Lightens dark spots

Stable

Routine for most Undetectable, types of light but assumed bodycolor cultured pearls; usually considered a step in standard processing rather than a treatment

Dyeing

Imparts or changes bodycolor

Usually stable, but some colors may fade

Common


Irradiation

Produces black, Stable gray, or blue-gray color in white or cream-colored pearls

Occasional

Sometimes detectable by a trained gemologist, but often requires advanced testing by a gemological laboratory*



Advisability

Ultrasonic cleaning

Never

Steam cleaning

Never

Warm, soapy water

Safe for occasional, thorough cleaning (if strung, be sure the string is completely dry before wearing)

For routine care, advise customers to wipe cultured pearls with a very soft, clean cloth after each wearing.


Alternatives Black chalcedony Coral Hematite

Cultured black Tahitian pearls, 13-15.6-mm, 18K gold, with diamonds (31 pearls)

Shell—mother-of-pearl 75

Peridot

Peridot has always been associated with light. The Egyptians called it the “gem of the sun.” Some believed that it protected its owner from “terrors of the night,” especially when it was set in gold. Others strung the gem on donkey hair and tied it around the left arm to ward off evil spirits. Today, Arizona’s San Carlos Indian Reservation is the world’s most commercially important producer. Peridot is usually transparent. It comes in an attractive range of colors, from brownish or yellowish green to greenish yellow. Customers will be attracted to the bright lime greens and more subdued olive greens of this lovely gem. This gem is relatively inexpensive and plentiful, and normally available in standard shapes and calibrated sizes up to about 5 cts. Larger stones are also fairly easy to find. Tumbled and faceted peridot is used for bead necklaces and bracelets, often combined with gems in contrasting colors—amethyst, citrine, and pink tourmaline, to name a few. The word peridot comes from the Arabic faridat, which means “gem.” Most peridot formed deep inside the Earth and was brought to the surface by volcanoes. Some has also come to Earth in meteorites, but this extraterrestrial peridot is extremely rare, and you’re not likely to see it in a retail jewelry store. Mineralogists refer to the stone as olivine. Peridot is one of the US birthstones for August (sardonyx is the other).

Sources Myanmar (Burma) Pakistan United States

76



Toughness

Fair to good


Reaction

Heat

Rapid or uneven heat can cause fracturing

Light

Stable

Chemicals

Attacked easily by sulfuric acid, and less easily by hydrochloric acid; can be attacked over a long period of time by acid perspiration

Topaz and peridot brooch with pearls set in yellow gold


Advisability

Ultrasonic cleaning

Risky

Steam cleaning

Never

Warm, soapy water

Safe

Imitations Glass Plastic Synthetic sapphire Synthetic spinel

Alternatives Chrysoberyl Demantoid garnet Emerald Jadeite jade Sapphire Topaz Tourmaline Tsavorite garnet Zircon

77

Pyrope Pyrope/Garnet

Pyrope is a mineral that’s part of the garnet group. The Greek word pyropos translates as “fiery-eyed,” and it’s easy to see how the gem got its name: The finest pyrope garnets have a glowing red color. Other pyrope colors range from medium to dark reddish orange to purplish red. Pyrope was popular with the Greeks and Romans. It was prominent in jewelry of the Victorian era (18371901), but it’s now in short supply and seldom available in sizes much larger than 2 cts. Collectors of antique jewelry prize the elaborate Victorian jewelry set with multitudes of small pyropes. Like other garnets, pyrope is a US birthstone for January. It’s occasionally called “Bohemian garnet,” after the region (now part of the Czech Republic) that was once an important source.

Sources South Africa United States


78

Hardness


Toughness

Fair to good


Reaction

Heat

Damaged by the heat of a jeweler’s torch; sudden temperature change can cause fracturing

Light

Stable

Chemicals



Advisability

Ultrasonic cleaning

Usually safe

Steam cleaning

Risky

Warm, soapy water

Safe

Pyrope (from Bohemia) bracelet

Imitations Glass Synthetic ruby

Alternatives Almandite garnet Rhodolite garnet Ruby Spinel Topaz Tourmaline Zircon

79

Rhodolite Rhodolite/Garnet

Rhodolite’s name is a modern composite of the Greek words rhodon, “rose,” “rose,” and lithos, lithos, “stone.” “stone.” It’ It’ss a mem ber of the garnet group, a mixture of almandite and pyrope. Technically, gemologists gemolo gists classify garnets by a combination of color and various tests, but to most dealers and other gem professionals, any predominantly purple garnet is rhodolite. rhodolite. Rhodolite’ Rhodolite’ss full color range includes light to dark purplish red through reddish purple. Rhodolite’s attractive color has made it one of the most valuable of the gems generally classified as “red” garnets. It’s also the best-selling garnet besides almandite, and enjoys a strong market supply and availability in a wide range of sizes. Like other garnets, rhodolite is a US birthstone for January January..

Sources Sri Lanka Tanzania Zimbabwe


80

Hardness


Toughness

Fair to good


Reaction

Heat


Light

Stable

Chemicals

Slowly attacked by hydrofluoric acid


Advisability

Ultrasonic cleaning

Usually safe

Steam cleaning

Never

Warm, soapy water

Safe

Fantasy cut rhodolite garnet (9mm x 21mm x 7mm) by Bart Curren set as pendant in 14K yellow gold


Alternatives Almandite garnet Pyrope garnet Ruby Spinel Topaz Tourmaline Zircon

Pink rhodolite garnet, rose octagon cut, 2.34 ct., from East Africa

81

Rose Quartz Rose Quartz/Quartz

Rose quartz is a lovely quartz variety that typically ranges in color from very light to medium dark pink. Often, it has numerous internal fractures that give it a cloudy translucence and a visual texture that’s almost like the veining in jadeite jade. Internal reflections sometimes give rose quartz specimens in the semitransparent range an intriguing “floating light” effect. Sometimes, a multitude of tiny inclusions provides the stone with a star effect. A cabochon cut combined with coating or mirror-like foil on the back enhances the star. Rose quartz is generally inexpensive. You’ll see the best color in the medium to large sizes: Small stones with good color can be harder to find. Its attractive color and good durability make this gem a great choice for bead necklaces and bracelets. Clean, close-to-transparent material might be faceted, while cabochon cuts are popular for stones set individually in metal mountings. Carvings from larger pieces make beautiful pendants.

Sources Brazil India Madagascar Sri Lanka


82

Hardness

7 on Mohs scale

Toughness

Good


Reaction

Heat

High heat can cause change or loss of color; sudden temperature change can cause fracturing

Light

Sometimes fades with prolonged exposure to bright light

Chemicals

Soluble in hydrofluoric acid and ammonium fluoride; very slightly soluble in alkalis


Advisability

Ultrasonic cleaning

Usually safe

Steam cleaning

Risky

Warm, soapy water

Safe


Alternatives Agate Kunzite Sapphire Spinel Star sapphire Topaz Tourmaline

Star rose quartz

83

Ruby Ruby/Corundum

15.97-ct. Burma ruby

Ruby has accumulated a host of legends over the centuries. In Sanskrit (the ancient sacred language of India), one of the terms for ruby is ratnaraj, “King of Gems.” People in India believed that rubies enabled their owners to live in peace with their enemies. In Burma (a ruby source since at least 600 AD —now called Myanmar), warriors wore rubies to make themselves invincible in battle. Many medieval Europeans wore rubies to guarantee health, wealth, wisdom, and success in love. As the US birthstone for July, and the world’s best-known and best-loved red gem, ruby still captivates the hearts and imaginations of gem professionals and consumers alike. Large, fine-quality rubies are extremely rare and valuable. But strong worldwide production and an array of treatments have increased availability and put rubies within the reach of most customers. Common cutting styles for ruby include mixed-cut ovals or antique cushions for transparent material, and cabochons or beads for translucent to opaque stones. Corundum has excellent toughness, and it’s harder than any other natural gem except diamond. This makes it ideal for rings as well as many other types of jewelry. The name ruby comes from the Latin word ruber, which means “red.” The most expensive ruby color is a deep, pure, vivid red. Stones a little pinkish, purplish, or orangy red are also considered rubies, but gem and jewelry professionals make careful distinctions between ruby and pink, purple, or orange sapphire. (Ruby and sapphire are both corundum varieties.) Generally, the difference depends on a combination of hue, tone, and saturation, but market culture and geography also make a difference. Gems that would be considered pink or purple sapphire in the US are often classified and sold as rubies in some Asian countries. It’s important to keep such regional trade practice variations in mind if you work in different markets, or with an international clientele. 84

Sources Afghanistan Kenya Madagascar Myanmar (Burma)

Considered to produce finest quality rubies

Sri Lanka

Often lighter in tone than rubies from Myanmar or Thailand

Tanzania Thailand

Mine production declined in the 1990s, but it’s still the world center for treatment and wholesale trade

Vietnam


Burmese ruby and diamond choker

Hardness

9 on Mohs scale

Toughness

Usually excellent, but stones with certain treatments or large fractures or inclusions can be less durable


Reaction

Heat

High heat can cause a change in color or clarity; it can also damage or destroy fracture- and cavity-fillings

Light

Generally stable, but heat from bright lights can cause oil to leak or dry out

Chemicals

Can harm fillings and remove oil; soldering flux containing boron, and firecoat made with boric acid powder, will etch the surface of even untreated stones

85


Purpose

Stability

Prevalence

Detection

Heat

Improves color and/or clarity appearance

Stable unless the stone is heated to very high temperatures

Very common; experts estimate that up to 95 percent of stones undergo some sort of heat treatment

May be detectable by a trained gemologist or gemological laboratory.* Can be undetectable, but assumed because of prevalence

Lattice diffusion Creates red color Stable under nor- Fairly common (heating to very in corundum mal conditions, high temperature but the red color in the presence of might be removed a coloring agent) in some stones if they’re repolished or recut


Occasional

Fracture-filling with oil or epoxy resin

Improves clarity appearance by hiding fractures. Colored oil or resin also improves color appearance

Fair. Heat and chemicals can damage or destroy the filling. Oil will probably dry out or discolor in time

Cavity-filling with epoxy resin or glass

Improves clarity appearance by hiding cavities; adds weight if the cavities are large

Fair. Heat and Common chemicals can damage or destroy the filling




1.02-ct. Burmese ruby

86


Advisability

Ultrasonic cleaning

Usually safe, but never for fracture- or cavity-filled stones

Steam cleaning


Warm, soapy water

Safe, but avoid strong detergents and vigorous scrubbing on oiled stones

Imitations Glass

Synthetics Czochralski Flame fusion

Ruby and diamond bracelet and necklace set

Floating zone Flux Hydrothermal

Alternatives Almandite garnet Pyrope garnet Rhodolite garnet Spinel Topaz Tourmaline

Vietnamese rubies from Luc Yen and Quy Chau set in jewelry (.33 - 1.94-ct)

87

Sapphire Sapphire/Corundum For centuries, sapphire has been associated with royalty and romance. The association was reinforced in 1981, when Britain’s Prince Charles gave a blue sapphire engagement ring to Lady Diana Spencer. Until her death in 1997, Princess Di, as she was known, charmed and captivated the world. Her sapphire ring helped link modern events with history and fairy tales. In ancient Greece and Rome, kings and queens were convinced that blue sapphires protected their owners from envy and harm. During the Middle Ages, the clergy wore sapphires to sym bolize Heaven, and ordinary folks thought the gem attracted heavenly blessings. In other times and places, people instilled sapphires with the power to guard chastity, make peace between enemies, influence spirits, and reveal the secrets of oracles. In folklore, history, art, and consumer awareness, sapphire has always been associated with the color blue. Its name comes from the Greek word sappheiros, which probably referred to lapis lazuli. Most jewelry customers think all sapphires are blue, and when gem and jewelry professionals use the word “sapphire” alone, they normally mean “blue sapphire.” In the trade, “blue sapphire” refers to stones ranging from very light to very dark greenish or violetish blue, as well as those in various shades of pure blue. Large, top-quality stones are rare, but blue sapphires in other sizes and grades are almost always available. Not all sapphires are blue, however. It’s a variety of the same species as ruby—corundum— and any corundum that doesn’t qualify as ruby is considered sapphire. Fancy sapphires, as they’re called, come in violet, green, yellow, orange, pink, purple, and intermediate hues. There are also parti-colored sapphires that show a combination of different colors. And some stones exhibit the phenomenon known as color change, most often going from blue in daylight or fluorescent lighting to purple under incandescent light. Sapphires can even be gray, black, or brown. Colorless sapphires were once popular diamond imitations, and in recent years they’ve staged a comeback as accent stones. Fancy sapphires are generally less available than blue ones, and some colors are scarce, especially in very small or very large sizes. Still, fancy sapphires create a rainbow of options for customers who like the romance associated with this gem, but who also want something out of the ordinary. Transparent sapphires of all colors are most often faceted. Translucent to opaque material is usually cut into cabochons or used for beads. Corundum is very hard and tough, and can be used in any type or style of jewelry, and worn by just about any customer. Sapphire is the US birthstone for September. Special trade terms for fancy sapphires include: • amethystine or plum sapphire—purple 88

• golden sapphire—yellow or orangy yellow • padparadscha sapphire—pinkish orange to orange-pink with light to medium tone and vivid saturation. The name comes from the Sinhalese term padmaragaya, or “lotus color.” (Sinhalese is the majority language of Sri Lanka.) • white sapphire—colorless

Sources Australia

Blue and fancy

Cambodia

Blue and fancy

China

Blue and fancy

India/Pakistan (Kashmir)

Famous historic source of fine blue sapphire, production is now very limited.

Kenya

Blue and fancy

Madagascar

Blue and fancy

Myanmar (Burma)

Blue and fancy

Nigeria

Blue

Pakistan

Fancy

Rwanda

Fancy

Sri Lanka

Blue and fancy

Tanzania

Blue and fancy

Thailand

Blue and fancy

United States

Blue and fancy

Vietnam

Blue and fancy

Padparadscha sapphire set in a ring with diamonds and blue sapphires


9 on Mohs scale

Toughness

Usually excellent, but stones with large fractures or inclusions, or some treatments, can be less durable


Reaction

Heat

High heat can cause change in color or clarity, and can damage or destroy fracture and cavity fillings

Light

Generally stable, but irradiated yellow or orange stones fade quickly; heat from bright lights can cause oil to leak or dry out

Chemicals

Can harm fillings and remove oil; soldering flux containing boron, and firecoat made with boric acid powder, will etch the surface of even untreated stones 89


Heat

Purpose Most commonly improves color and/or clarity appearance

Stability Stable unless the stone is heated to very high tem peratures

Prevalence

Very common for blue sapphires (experts estimate that up to 95 percent of stones undergo some sort of heat treatment); common for golden sapphires Common for almost all colors

Detection May be detectable by a trained gemologist or gemological laboratory.* Can be undetectable, but assumed because of prevalence

Lattice diffusion Creates almost (heating to very any color in high temperature corundum in the presence of a coloring agent)

Stable under normal conditions, but the color might be removed in some stones if they’re repolished or recut


Fracture filling with oil or epoxy resin

Improves clarity appearance by hiding fractures. Colored oil or resin also improves color appearance

Fair to good. Heat Rare for all and chemicals can colors damage or destroy the filling. Oil will probably dry out or discolor in time.


Cavity filling with epoxy resin or glass

Improves clarity appearance by hiding cavities; adds weight if the cavities are large

Fair. Heat and chemicals can damage or destroy the filling

Rare for all colors


Irradiation

Produces yellow Extremely or orange from poor. Color colorless, light fades quickly yellow, and some (in minutes to very light blue days). material

Rare

Detectable by “fade test.” (Place the stone under bright light for a couple of days)


90


Advisability

Ultrasonic cleaning


Steam cleaning


Warm, soapy water

Safe, but avoid strong detergents and vigorous scrub bing on oiled stones

Imitations Glass Synthetic spinel

Synthetics Czochralski Flame fusion Floating zone Flux

Sapphire and diamond necklace

Hydrothermal * If there is any doubt, send the gem to a gemological laboratory for verification.

Alternatives Alexandrite Amethyst Aquamarine Chrysoberyl Citrine Kunzite Malaya garnet Rhodolite garnet Spessartite garnet Spinel Tanzanite Topaz Tourmaline Zircon

91

Shell

Since prehistoric times, shell has been a by-product of the quest for food by cultures living around the Earth’s rivers, lakes, seas, and oceans. Long ago, humans began using attractive shells for jewelry. Because it’s durable and easy to fashion, shell has remained popular as a gem material right up t o the present. Its close association with water—especially the sea—gives it an aura of romance and magic similar to that of pearl and coral. Ranging from translucent to opaque, shell comes in many colors. The most common colors are white and various shades of gray, brown, yellow, orange, and pink. Some shell has bands or patterns of different colors. Other material shows the iridescent effect known as orient. Its abundance, low cost and availability in large pieces make shell ideal for beads, cabochons, inlays, and carvings. Color-banded material is ideal for cameos because it allows the creation of designs that contrast dramatically with their backgrounds. Some of the finest shell cameos appear in jewelry from the mid-1800s. During those years, Queen Victoria’s fondness for cameos created a fashion trend that inspired skilled gem artists to produce masterpieces of artistic and technical beauty. Much of the shell used in today’s mainstream jewelry market—including imaginative designer pieces— comes from the mollusks that are also used for pearl culturing. Various species of shellfish provide material for the jewelry sold in tourist and resort locales. The types of shell you’re most likely to see in a retail jewelry store include: 92

• Mother-of-pearl—the inside of the shell from a pearl-producing mollusk. The bodycolor is usually white, but it can also be brown or gray. Mother-of-pearl’s rich luster and frequent display of orient come close to duplicating the appearance of pearl (but only on one side of the material). • Abalone shell—mother-of-pearl that’s usually from the mollusk known to scientists as haliotis. It typically has dark gray or brown bodycolor and striking orient. Abalone from the waters around Australia and New Zealand is often called Paua shell. Its bright blue and green orient gives it the look of a peacock’s tail feathers. • Conch shell—obtained from the giant queen conch. Its color usually ranges from pale to fairly bright pink or orange. The color is often layered or banded with white, and some shells have a pattern described as flame-like. The queen conch also produces a material known as conch pearl. It has an attractive porcelain-like sheen, but it lacks the pearly coating of a true pearl. The sunrise-pink color and flame patterns of fine specimens make them treasures for gem connoisseurs, especially in Europe, the Middle East, and Asia. • Helmet shell—the type most often used for cameos. It’s generally layered in two colors: white and brown, or white and orange.

Gem-inlaid shells are used in producing such jewelry items as cufflinks, earrings and pins

• Ammonite—the fossilized shells of squid-like animals that flourished about 65 million years ago. (Their closest living relative is the chambered nautilus.) The shells have a coiled shape, and specimens with iridescence are the ones used in jewelry, sometimes as assembled stones with quartz tops.

93

Sources Australia

Abalone, mother-of-pearl

Canada

Ammonite

Italy

A center for shell carving

Madagascar

Helmet

New Zealand

Abalone

United States

Abalone, conch, mother-of-pearl, ammonite

West Indies

Conch, helmet


31/2 on Mohs scale

Toughness

Fair


Reaction

Heat

Blackens in the flame of a jeweler’s torch

Light

Generally stable, but conch shell and some dyed material gradually fades in sunlight

Chemicals

Easily attacked by acids


Purpose

Stability

Prevalence

Detection

Dyeing

Produces a variety of colors

Fair. Dyes may fade

Common



Black and white shell cameo set in gold

94


Advisability

Ultrasonic cleaning

Risky

Steam cleaning

Risky

Warm, soapy water

Safe


Alternatives Agate Carnelian Coral Cultured pearl Fire agate Jadeite jade Moonstone

Cameos fashioned from mother of pearl shell

Nephrite jade Onyx Rose quartz Sardonyx

95

Smoky Quartz Smoky Quartz/Quartz

Smoky quartz is one of the most common and inexpensive transparent gems on the market. Its color varies from light t o dark brown, and some stones are so dark they’re almost black. Smoky quartz is a traditional gem in the Scottish Highlands. There, it’s also known as cairngorm, after the Cairngorm Mountains of Scotland, an old but now depleted source. Very dark smoky quartz—often called morion—was popular in the somber mourning jewelry of the late Victorian period (1861-1901). You’ll seldom see smoky quartz in sizes under a carat, but larger stones are always available in most standard shapes and sizes. Smoky quartz has good durability, so it’s suitable for any type of jewelry. Its color makes it a good choice as a gemstone accent for warm yellow and orange wardrobe colors. Because of its color, many consumers (and some professionals) confuse smoky quartz with topaz, but topaz is a different gem species.

Sources Brazil Switzerland United States


96

Hardness

7 on Mohs scale

Toughness

Good


Reaction

Heat

High heat can cause change or loss of color; sudden temperature change can cause fracturing

Light

Stable

Chemicals



Purpose

Stability

Prevalence

Detection

Irradiation

Produces smoky quartz from rock crystal (colorless quartz)

Excellent

Common

Undetectable (duplicates processes that color natural material)

Heat

Lightens the color of very dark material

Excellent

Occasional

Undetectable (duplicates processes that occur naturally)


Advisability

Ultrasonic cleaning

Usually safe

Steam cleaning

Risky

Warm, soapy water

Safe

Alternatives Chalcedony Citrine Moonstone Topaz Tourmaline Zircon

Faceted and rough smoky quartz

8500 ct. smoky quartz

97

Spessartite Spessartite/Garnet

Customers who think all garnets are red will be surprised and delighted with spessartite (also known as spessartine). Some gems of this garnet species are a bright and lively orange. Others range from medium-light to dark yellowish or reddish orange. Market supply is sometimes limited, but rounds and fancy shapes are normally available in sizes up to 10 cts. You can usually also find larger stones with a little searching. Prices for spessartite—especially stones from more remote locations and those with a bright orange color—are generally a little higher than those for red garnets like almandite and pyrope. The gem’s name comes from Spessart, a district in the state of Bavaria, Germany, that was once an important source. Customers born in January are among those most likely to be interested in spessartite, because it offers a birthstone color that’s a little different.

Sources Brazil Madagascar Myanmar (Burma) Namibia Sri Lanka United States


98

Hardness


Toughness

Fair to good


Reaction

Heat


Light

Stable

Chemicals

Very slowly attacked by hydrofluoric acid


Advisability

Ultrasonic cleaning

Usually safe, but risky for stones with large or numerous inclusions or fractures

Steam cleaning

Never

Warm, soapy water

Safe

Imitations Glass Synthetic sapphire

Alternatives Amber Carnelian Citrine Fire opal Malaya garnet Sapphire Spinel Topaz Tourmaline

99

Spinel Spinel is a good candidate for the title of “History’s Most UnderAppreciated Gem.” Some ancient mines that supplied gems for royal courts from Rome to China produced spinels, but they were usually confused with better-known stones like ruby and sapphire. Some of the world’s most illustrious “rubies” are actually spinels. One of these is the Black Prince’s Ruby, a polished but unfaceted red spinel that weighs about 170 cts. It appears in historical records dating back to the 1300s, and it’s a central stone in the British Imperial State Crown. Modern technology hasn’t helped spinel’s confused identity, either—at least, as far as the general public is concerned. This is largely due to the widespread use of synthetic spinel as an imitation for many other gems. Most customers don’t even know there’s a natural version of t he stone. Limited availability also contributes to spinel’s lack of public recognition. Gem-quality material is typically transparent and faceted, but it’s hard to find in sizes larger than 5 cts. Spinel’s color range includes violet, blue, orange, red, pink, and purple. Blue spinels are often grayish and subdued, but the best are a deep rich color. The reds can rival fine ruby. And the vivid orange to orange-red stones merit their trade name—flame spinel. Some spinels show color-change, usually turning from grayish blue in daylight or fluorescent light to purple under incandescent light. In addition to its attractive colors, spinel is a hard, tough stone that’s suitable for daily wear in any type of jewelry. It will always be popular with customers who like beautiful and unusual gems.

Sources Cambodia Myanmar (Burma)

Known for fine-quality pink and red spinels

Sri Lanka Tanzania Thailand


100

Hardness

8 on Mohs scale

Toughness

Good

Stability Environmental factor

Reaction

Heat

High heat may cause the color to fade

Light

Stable

Chemicals

Stable


Advisability

Ultrasonic cleaning

Usually safe

Steam cleaning

Usually safe

Warm, soapy water

Safe


Red spinel from Myanmar (Burma)

Synthetic sapphire

Synthetics Flame fusion Flux

Alternatives Almandite garnet Amethyst Aquamarine Fire opal Kunzite Malaya garnet Morganite Pyrope garnet Rhodolite garnet Ruby Sapphire Spessartite garnet Tanzanite Topaz Tourmaline

Blue spinel

101

Star Ruby Star Ruby/Corundum

According to Eastern folklore, star rubies ward off evil and bring good luck to their owners. But the market supply of these auspicious gems is generally very limited. Fine stones are rare prizes eagerly sought by collectors and connoisseurs. Star rubies vary from semitransparent to opaque and from light to dark red or purple-red. They display a phenomenon called asterism. It’s caused by tiny needle-like inclusions that reflect and scatter light within the stone. Star ruby’s star usually has six rays, and it requires skilled cabochon cutting to bring it out. The finest star rubies are almost transparent, with a strong deep color that rivals non-phenomenal rubies. They show a sharp, complete star that glides smoothly back and forth as you rock the stone gently. Star rubies display their optical charms best when they appear as center stones in elegant ballerina-style ring settings, surrounded by flashing diamond baguettes. The typical size range for star rubies is 1 ct. to 10 cts., but much larger stones exist. One of the largest fine-quality star rubies on public display is the Smithsonian Institution’s 137-ct. Rosser Reeves Ruby. Along with ruby, star ruby is considered a US birthstone for July.

102

Sources India Kenya Myanmar (Burma) Sri Lanka Tanzania Thailand


Star ruby from Tanzania

Hardness

9 on Mohs scale

Toug ughn hneess

Excell lleent exc xceept in sto tone ness wit ith h re repe peaate ted d tw twin inni ning ng or large fractures


Reaction

Heat

High heat can burn oil and change the stone’s color or the quality of the star effect

Light


Chemicals

Can remove oil; soldering flux containing boron, and firecoat made with boric acid powder, will etch the surface of the stone

103

Treatments Treatment Heating followed by slow cooling

Purpose Creates or improves the star effect

Stability Stable unless the stone is heated to very high temperatures and then cooled rapidly

Prevalence

Detection

Occasional

Undetectable

Oiling or dyeing

Hides cracks and improves clarity and color appearance

Fair. Can be damaged or destroyed by high heat and solvents. Oil will probably dry out or discolor in time.

Occasional


Lattice diffusion

Creates the star effect

Stable under normal conditions, but the star effect can be damaged damaged or or destroyed if the stone is repolished or recut

Rare



104


Advisability

Ultrasonic Cleaning

Safe except for oiled stones and those with fractures

Steam Cleaning


Warm, soapy water

Safe, but avoid strong detergents and vigorous scrubbing on oiled stones

Imitations Glass or other inexpensive material engraved with a star on the backside of the stone, or backed with metallic foil engraved with a star design.

Synthetics Flame fusion

Alternatives Star almandite Star moonstone Star rose quartz Star sapphire Star spinel

105

Star Sapphire Star Sapphire/Corundum

A cabochon-cut star sapphire characteristically shows a six-rayed star, caused by needle-like “silk” inclusions that reflect and scatter light. Star sapphires range from semitransparent to opaque. They come in many of the same colors as non-phenomenal sapphires, but supplies of most colors are limited: Green star sapphires are rare, and yellow or orange ones are very rare. Black star sapphire, which ranges from translucent to opaque, is often very dark brown, green, or blue, rather than true black. It’s the most available and least expensive natural star stone, and it’s especially popular for men’s jewelry. Modern heat treatments that remove inclusions from rough material have made fine-quality star sapphires rare. Marketed gems typically range from 1 ct. to 10 cts. in size, but you can sometimes find larger stones as well. The American Museum of Natural History’s collection includes one of the world’s largest and most spectacular blue star sapphires—the 153-ct. Star of India. Some traditions say that star sapphire is a stone of destiny, and that its star acts as a guiding light and protects its wearer against evil. To medieval Christians, the three intersecting bands that form the star represented the spiritual virtues of Faith, Hope, and Charity. Today, star sapphire provides a phenomenal September birthstone alternative.

106

Sources Australia Kenya Myanmar (Burma) Sri Lanka Tanzania Thailand


9 on Mohs scale

Toughness

Excellent except in stones with repeated twinning or large fractures


Reaction

Heat

High heat can burn oil and change the stone’s color or the quality of the star effect

Light


Chemicals

Can remove oil; soldering flux containing boron, and firecoat made with boric acid powder, will etch the surface of the stone

107


Purpose

Stability

Prevalence

Detection

Heating followed by slow cooling

Creates or improves the star effect

Stable unless the stone is heated to very high temperatures and then cooled rapidly

Occasional

Undetectable

Oiling or dyeing

Hides cracks and improves clarity and color appearance

Fair. Can be damaged or removed by high heat and solvents. Oil will probably dry out or discolor in time.

Occasional


Lattice diffusion

Creates the star effect

Stable under normal conditions, but the star effect can be damaged or destroyed if the stone is repolished or recut

Rare



Care and Cleaning

108

Type of Cleaning

Advisability

Ultrasonic cleaning


Steam cleaning


Warm, soapy water

Safe, but avoid strong detergents and vigorous scrub bing on oiled stones

Imitations Glass or other inexpensive material engraved with a star on the backside of the stone, or backed with metallic foil engraved with a star design.

Synthetics Flame fusion

Alternatives Star moonstone Star rose quartz Star ruby Star spinel A 3,965-ct. sapphire from an area of Sri Lanka that is known to produce star sapphires of over 500 cts.

109

Tanzanite Tanzanite Tanzanite is relatively new to the colored stone galaxy. This transparent blue gem first turned up in 1962, scattered on the Earth’s surface in northern Tanzania, a country in eastern Africa. Scientists identified it as a variety of the mineral zoisite. About five years later, a prospector discovered a large deposit of it in the same area, and serious mining began. Tiffany & Company recognized its potential as an international seller and made a deal to become its main distributor. Tiffany named the gem after the country it came from, and promoted it with a big publicity campaign in 1968. Almost overnight, tanzanite was popular with leading jewelry designers and other gem professionals, as well as with customers who had an eye for beautiful and unusual gems. Tanzanite’s public recognition and popularity have grown steadily. But there have been wide fluctuations in the gem’s supply and price level, due mostly to Tanzania’s volatile political, social, and economic conditions. That country remains the gem’s only source, so the outlook for long-term availability is also doubtful. (You can keep up with its market variability by reading industry publications, attending trade shows, and talking to suppliers.) Tanzanites are heat-treated to produce colors that include light to dark violetish blue and bluish purple, as well as pure blue. Rich, deep hues are valued most, but you’ll usually see these only in stones weighing 5 cts. or more. This is mainly because of decisions made during the cutting process. Tanzanite typically shows strong pleochroism, which means it displays different colors from different directions. It usually looks violetish blue from some directions, purplish from others. Predominately blue tanzanite is generally worth more per carat, but because of the way tanzanite crystals grow, a cutter can usually get a bigger stone by orienting the gem to show the purple color. With small rough, size is normally the main consideration. While the trade considers the pure blue stones to be “top” grade, some customers actually prefer the lighter and more purplish colors. This means you can offer them what they like best at an affordable price. Tanzanite is special-care gem for two reasons: sensitivity to thermal shock and the potential for cleavage. Sometimes the temperature change between the hot lights of the display case and the chilly glass countertop in an air-conditioned showroom can be enough to develop cleavages in tanzanite. Because of its susceptibility to cleavage, tanzanite shouldn’t be handled carelessly. If you’re helping young or active customers select tanzanite jewelry, try suggesting pieces that won’t be too exposed to accidental bumps—pendants and earrings are good choices. For everyday wear, it’s best to select jewelry that’s designed to protect the stone. 110

Sources Tanzania



Toughness

Fair to poor, due to cleavage and sensitivity to thermal shock


Reaction

Heat

Sudden temperature change can cause cracking

Light

Stable

Chemicals

Attacked by hydrochloric and hydrofluoric acid


Purpose

Stability

Prevalence

Detection

Heat

Produces tanzanite color in trans parent brownish material

Stable

Routine

Undetectable, but assumed because of prevalence


Advisability

Ultrasonic cleaning

Never

Steam cleaning

Never

Warm, soapy water

Safe

Imitations Glass Synthetic sapphire Synthetic spinel Synthetic spinel triplet

Alternatives Amethyst Iolite Sapphire Spinel

111

Tiger’s-Eye Tiger’s-Eye/Quartz

Tiger’s-eye is one of the top-selling phenomenal gems. Varying from translucent to opaque, it comes in warm earth tones that include brown, brownish yellow, and reddish brown. Its main distinguishing characteristic is its “eye,” called chatoyancy. Tiger’s-eye’s chatoyancy is different from the chatoyancy in cat’s-eye chrysoberyl. For one thing, it usually has a wavy appearance, rather than a straight, sharp look. Also, tiger’s-eye can be cut in many ways, even flat, while cat’s-eye has to be fashioned as a cabochon to bring out the phenomenon. Explanation for these differences lies in their different “eye” causes: In tiger’seye, reflections of light from the fibrous structure of the gem itself create the eye, while in cat’s-eye, the eye comes from inclusions rather than structure. Tiger’s-eye is inexpensive and available in most standard sizes. It’s a popular material for cabochons (usually with flat backs), beads, tablets, cameos, and intaglios. Good toughness makes tiger’s-eye a great gem for everyday wear, and it’s a frequent choice for men’s jewelry Other chatoyant quartz gem varieties are scarcer and usually more expensive. These include: • Hawk’s-eye or falcon’s eye—grayish blue material with chatoyancy like tiger’s-eye • Zebra tiger’s-eye—tiger’s-eye with grayish or blue streaks • Cat’s-eye quartz—brownish yellow, brownish green to greenish yellow. Shows a true cat’s-eye effect. (It must be cut as a cabochon to show the eye.)

Sources India South Africa Sri Lanka


112

Hardness

7 on Mohs scale

Toughness

Good


Reaction

Heat


Light

Stable

Chemicals


Treatments Treatment Bleaching (sometimes followed by plastic coating)

Purpose Lightens the color. Plastic coating seals the fibrous structure and prevents contamination with dirt and foreign matter

Stability

Prevalence

Excellent

Common

Heat

Produces a reddish brown color

Excellent

Common

Dyeing

Adds various color

Usually good. Common Some dyes may be affected by solvents, or fade with prolonged exposure to bright light.

Detection Undetectable, but light brownish yellow color is a strong indication of treatment

Undetectable




Advisability

Ultrasonic cleaning

Usually safe

Steam cleaning

Risky

Warm, soapy water

Safe


Alternatives Cat’s-eye chrysoberyl Cat’s-eye tourmaline 113

Topaz

Most authorities agree that the name topaz comes from Topazios, the old Greek name for an island in the Red Sea, now called Zabargad. (The island never produced topaz, but it was once a source of peridot, which was confused with topaz before the development of modern mineralogy.) Some scholars trace the origin back to Sanskrit (an ancient language of India) and the word topas or tapaz, meaning “fire.” The ancient Greeks believed that topaz gave them strength. In Europe during the Renaissance (the period from the 1300s to the 1600s) people thought that topaz could break magic spells and dispel anger. For centuries, many people in India have believed that topaz worn above the heart assures long life, beauty, and intelligence. Most consumers are under the impression that topaz is an easy gem to recognize. But what they might think of as topaz could actually be the more common citrine and smoky quartz. This confusion shows when you’re displaying topaz jewelry and your customer says something like “I didn’t realize topaz was so expensive” or “Isn’t topaz brown?” You will need to clear up these misunderstandings before you go further in your presentation. Topaz actually has an exceptionally wide color range that, besides brown, includes various tones and saturations of blue, green, yellow, orange, red, pink, and pur ple. Colorless topaz is another option. The color varieties are often identified simply by hue—blue topaz, pink topaz, and so forth—but there are also a couple of special trade names: • Imperial topaz—medium reddish orange to orangered. This is one of the most expensive colors. • Sherry topaz—yellowish brown or brownish yellow to orange. This term comes from the color of sherry wine. (Stones in this color range are often called precious topaz to help distinguish them from the less expensive citrine and smoky quartz.)

114

Strong output from sources around the world and treatments that expand the range of usable gems guarantee a steady supply of topaz. However, market availability varies according to color. Blue topaz is abundant, and there’s usually plenty of sherry topaz, but the supply of imperial, red, purple, and pink tends to be limited. Most colors are available in standard faceted shapes, but the sizes differ from color to color. Blue usually ranges from 1 ct. to 25 cts., while other colors normally run from 1 ct. to 10 cts. You might also find some larger stones, especially in sherry or blue. Generally, red is the most valuable topaz color, but market prices and preferences vary from country to country. Imperial topaz brings highest prices in Japan and Germany. Japanese buyers also favor pink topaz. The biggest market for blue topaz is in the US, where it provides a gem alternative that’s lower in cost and more intense in color than aquamarine.

Topaz carving from Idar-Oberstein

The biggest faceted gem (by weight) ever recorded is a topaz in the collection of the Smithsonian Institution. Named the “American Golden,” it’s a light yellow stone that weighs 22,982 cts. (4.60 kg or 10.14 lb.) and measures 17.3 cm ˘ 14.9 cm ˘ 9.2 cm (6.7 in. ˘ 5.8 in. ˘ 3.6 in.). Today, topaz is one of the US birthstones for November. (The other is citrine.) Topaz is a hard stone, but it can develop cleavage. Keep this in mind when you’re showing jewelry, and advise customers to be a little extra careful when wearing this gem.

Sources Australia Brazil Madagascar Mexico Myanmar (Burma) Namibia Nigeria Pakistan Sri Lanka United States

115


8 on Mohs scale

Toughness

Poor due to cleavage


Reaction

Heat

High heat can alter color; sudden temperature change can cause breaks

Light

Generally stable, but some brown stones fade

Chemicals

Affected very slightly


Purpose

Stability

Prevalence

Detection

Heat

Changes some yellow, orange, or brown material to pink

Stable

Common

Undetectable, but usually assumed because of prevalence

Irradiation followed by heat

Produces various shades of blue from colorless material

Stable

Routine (almost all medium to dark blue topaz is produced by treatment)

Usually undetectable, but assumed because of prevalence. Occasionally detectable by a gemological laboratory. Caution: May very rarely be dangerously radioactive*


Bue topaz

9.73-ct. topaz from Brazil

116


Advisability

Ultrasonic cleaning

Never

Steam cleaning

Never

Warm, soapy water

Safe


Alternatives Aquamarine Citrine Hessonite garnet Kunzite Malaya garnet Morganite Sapphire Smoky quartz Spessartite garnet Spinel

Topaz crystal

Tourmaline Zircon

117

Tortoise Shell

Tortoise shell is an organic gem material from the shell of the hawksbill sea turtle. It ranges from semitransparent to translucent, with a mottled appearance that’s usually yellow and brown, but occasionally black and white. For centuries, artisans used tortoise shell to make jewelry and other items, including combs and decorative furniture inlays. It was also a popular material for eyeglass frames and guitar picks. Hawksbill turtles are an endangered species. Since the 1970s, they’ve been protected under the UN Convention on International Trade in Endangered Species of Fauna and Flora (CITES). Most of the more than 100 countries that are parties to the convention also have supporting laws or regulations that ban commerce in tortoise shell. US federal law prohibits the import or sale of items made from hawksbill shell, unless they can be proven to be at least 100 years old. Pieces that aren’t that old, but were made and privately owned before 1974, can be legally purchased from individuals or estates, but only for a collection, and not for resale.


118

Hardness

21/2 on Mohs scale

Toughness

Fair


Reaction

Heat

Softens at the temperature of boiling water; high heat darkens, then burns the material

Light

May darken with age

Chemicals

Attacked by nitric acid


Purpose

Stability

Prevalence

Detection

Lamination (pieces are softened and joined together with heat and pressure)

Made thicker material for carving

Variable, depending on how well the layers were joined

Occasional




Advisability

Ultrasonic cleaning

Never

Steam cleaning

Never

Warm, soapy water

Safe, but hard-bristle brushes can leave scratches

Imitations Plastic

Alternatives

Tortoise shell box

Agate Amber Sardonyx Shell

119

Tourmaline

People have probably used tourmaline as a gem for centuries, but until the development of modern mineralogy, they identified it as some other stone (ruby, sapphire, emerald, and so forth) based on its color. Portuguese explorers, for example, discovered deposits of green tourmaline in Brazil in the mid1500s, but they thought it was emerald. The confusion about the stone’s identity is even reflected in its name, which comes from toramalli, which means “mixed gems” in Sinhalese (a language of Sri Lanka). In the late 1800s, tourmaline became known as an American gem through the efforts of Tiffany gemologist George F. Kunz. He wrote about the tourmaline deposits of Maine and California, and praised the stones they produced. In spite of its American roots, tourmaline’s biggest market was in China, where the imperial court prized tourmaline as a material for small carvings and utilitarian objects like snuff bottles. The supply of tourmaline began to expand during the first half of the twentieth century, when Brazil yielded some large deposits. Then, beginning in the 1950s, additional finds appeared in countries around the world. Tourmalines come in a wide variety of exciting colors. In fact, tourmaline has one of the widest color ranges of any gem species. It occurs in various shades of almost every hue, and there are a number of trade names for its color varieties: • Rubellite—pink, red, purplish red, orangy red, or brownish red. (Some in the trade argue that pink tourmaline shouldn’t be called rubellite.) • Indicolite—dark violetish blue, blue, and greenish blue. • Paraíba tourmaline—intense violetish blue, greenish blue, or blue from the state of Paraíba, Brazil. (This variety was discovered in 1988.) • Chrome tourmaline—intense green. (Much of this is colored by vanadium, the same element that colors many Brazilian and African emeralds.) 120

• Parti-colored tourmaline—tourmaline with more than one color. One of the most common combinations is green and pink, but many others are possible. • Watermelon tourmaline— pink in the center and green around the outside. Crystals of this material typically have a pink core surrounded by green, and they’re cut in slices. Some tourmalines also show chatoyancy. Cat’s-eye tourmalines are most often green, blue, or pink, with an eye that’s softer and more diffused than the eye in fine cat’s-eye chrysoberyl. This is because, in tourmaline, the effect is caused by thin tube-like inclusions that occur naturally during the gem’s growth. The inclusions are larger than the inclusions in cat’s-eye chrysoberyl, so the chatoyancy isn’t as sharp. Like other cat’s-eyes, these stones have to be cut as cabochons to bring out the effect.

Sources Afghanistan Brazil

Bi-colored emerald cut tourmaline set with diamonds

Major source

Kenya Madagascar Mozambique Myanmar (Burma) Namibia Pakistan Russia United States



Toughness

Fair


Reaction

Heat

High heat can alter color; sudden temperature change can cause fracturing

Light

Generally stable

Chemicals

None

121


Purpose

Heat

Irradiation

Stability

Prevalence

Detection

Lightens very Stable dark green or blue-green stones; converts brownish purple stones to “rose” pink; produces bright greenish blue to yellowish green stones from grayish Paraíba material

Common

Undetectable

Produces deep pink, red, or pur ple from very light pink, green, blue, or colorless material; converts some light yellow or green material to a darker yellow or orange; turns some green stones into red and green particolored

Fair to good. Color may fade under high heat or very prolonged exposure to bright light.

Common for pink, red, and purple. Occasional for yellow, orange, and parti-color.

Undetectable

Occasional

Undetectable

Acid

Improves the appearance of cat’s-eye stones

Stable

Sealing tubes in cat’s-eye material with plastic or epoxy resin

Prevents dirt from getting into the tubes that cause the cat’s-eye effect

Fair. Heat and Occasional solvents can damage or destroy the sealant.



Care and Cleaning

122

Type of Cleaning

Advisability

Ultrasonic cleaning

Risky

Steam cleaning

Risky

Warm, soapy water

Safe

Imitations Glass Synthetic ruby Synthetic sapphire Synthetic spinel

Alternatives Almandite garnet Amber Amethyst Aquamarine Cat’s-eye chrysoberyl

Freshwater cultured pearl torsade with decorative clasp featuring tourmaline slices.

Chrysoberyl Citrine Emerald Fire opal Kunzite Malaya garnet Morganite Peridot Pyrope garnet Rhodolite garnet Ruby Sapphire Smoky quartz Spessartite garnet Spinel Tanzanite Topaz Tsavorite garnet Zircon

123

Tsavorite Tsavorite/Grossularite/Garnet

Kenya’s Tsavo National Park is home to some of the largest remaining populations of Africa’s legendary animals, including lions, elephants, giraffes, and zebras. In the early 1970s this wildlife wonderland also gave the world an exciting new gem. Scientists identified the stone as a transparent green variety of the garnet species known as grossularite. In 1974, Tiffany & Company introduced it to the US market as tsavorite. (It’s often called tsavolite in Europe.) Only a few sources of tsavorite have been discovered, so supplies of it are limited. Because of its often delightfull y bright color, it has become one of the most sought-after and expensive garnets. Its color ranges from light to dark—but always intense— yellowish green or green. You’re likely to see tsavorite only in fairly small sizes—from about 50 pts. to 3 cts. The largest faceted tsavorite on record weighs a little under 24 cts. Because tsavorite is part of the garnet family, it’s a US birthstone for January. Its intense green color and the fact that it’s generally untreated make it an exotic, high-quality alternative to emerald. It’s an intriguing twentieth century gem that can add zest to any customer’s jewelry collection.

Sources Kenya Tanzania


124

Hardness

7 to 7 1/2 on Mohs scale

Toughness

Fair to good


Reaction

Heat


Light

Stable

Chemicals



Advisability

Ultrasonic cleaning

Usually safe, but risky if the stone contains liquid inclusions

Steam cleaning

Never

Warm, soapy water

Safe

Tsavorite garnet and diamonds in gold ring

Imitations Glass Synthetic emerald Synthetic spinel

Alternatives Demantoid garnet Emerald Peridot Tourmaline

125

Turquoise

Turquoise is one of the world’s most ancient gems. Archaeological excavations revealed that Egyptian royalty wore turquoise jewelry as early as 5500 BC, and Chinese artisans were carving it more than 3,000 years ago. Turquoise is the national gem of Tibet, and has long been considered a stone that guarantees health, good fortune, and protection from evil. Turquoise was a ceremonial gem and a medium of exchange for Native American tribes in the southwestern US. They also used it in their jewelry and amulets. The Apaches believed that turquoise attached to a bow or firearm increased a hunter’s or warrior’s accuracy. The gem’s name comes from the French expression pierre tourques, or “Turkish stone.” The name, which originated in the thirteenth century, reflects the fact that the material probably first arrived in Europe from Turkish sources. Turquoise can be translucent to opaque, with a color that usually ranges from light to medium blue or greenish blue. It’s often mottled, and sometimes has dark splotches. It might also have veins of matrix running through it (matrix is its surrounding rock). In the material known as spiderweb turquoise, fine seams of matrix form attractive web-like patterns. The most valuable turquoise is an even medium blue, with no matrix, and the ability to take a good polish. Turquoise is plentiful and available in a wide range of sizes. It’s used for beads, cabochons, carvings, and inlays. Although well known to consumers, its popularity in the mainstream jewelry industry comes and goes. The biggest and most permanent market is in the American Southwest. It’s also popular elsewhere, among customers who are captivated by that region’s mystery and romance, as well as by the blue of its skies. Turquoise is one of the December birthstones. (Zircon is the other option for that month.) 126

Sources China Iran

Historical source of the finest material (known as Persian turquoise): No longer commercially important

United States



Toughness

Generally fair to good


Reaction

Heat

High heat can cause discoloration and surface damage

Light

Stable

Chemicals

Dissolves slowly in hydrochloric acid; can be discolored by chemicals, cosmetics, and even skin oils or perspiration

127


Purpose

Stability

Prevalence

Detection

Impregnation with wax or plastic (sometimes with dye added)

Improves the color and luster of pale material; plastic also improves dura bility

Excellent to fair. Plastic is stable under normal conditions, but wax may gradually deteriorate and discolor.

Common

Detectable by a trained gemologist or a gemological laboratory*

Painting matrix with black shoe polish or similar colorants

Makes the matrix a desirable color

Fair. Solvents can damage or destroy the treatment.

Common


Backing with epoxy resin

Adds thickness, strength, and weight to pieces otherwise too thin to cut

Good under normal conditions. Heat or solvents can damage or destroy the epoxy backing.

Common

Detectable by a trained gemologist or a gemological laboratory if the stone is unmounted*

Filling cavities with metalloaded epoxy

Hides cavities and imitates pyrite inclusions

Fair. Heat or solvents can damage or destroy the fillings, and they may eventually separate even under normal conditions.

Occasional



128


Advisability

Ultrasonic cleaning

Never

Steam cleaning

Never

Warm, soapy water

Safe

Imitations Glass Plastic “Reconstructed turquoise,” usually made of various powdered minerals— not turquoise—dyed and bonded with plastic, epoxy resin, or similar substances.

Synthetics Synthetic turquoise was produced on a limited basis in the 1980s, but it was never widely available on the market. A trained gemologist or gemological laboratory can identify the material. (If there is any doubt, send t he gem to a gemological laboratory for verification.)

Alternatives Agate Chrysocolla chalcedony Jadeite jade Lapis lazuli Malachite Nephrite jade

Turquoise and diamond pin in the form of a closed flower

129

Zircon

Many people have heard of zircon but never seen it. Mostly, this is because of colorless zircon’s wide use as a diamond simulant in the early 1900s. It was long ago replaced in that role by more convincing look-alikes, but its name still means “imitation” to many people. That’s unfortunate—or, rather, it creates an opportunity for creative customer education—because zircon is a beautiful colored stone with its own fair share of folklore and charm. Zircon is one of the US birthstones for December (the alternate is turquoise). In the Middle Ages, this gem was thought to induce sound sleep, drive away evil spirits, and promote riches, honor, and wisdom. Many scholars think the stone’s name comes from the Arabic word zarkun, meaning “cinnabar” or “vermilion.” Others believe the source is the Persian word zargun, or “gold colored.” Considering zircon’s color range, either derivation seems possible. The most common color for the zircons on today’s market is a distinctive greenish blue that’s often called “zircon blue.” Others include green, yellow, orange, red, brown, and even purple. The colors are often light and muted, but the finest stones have strong, rich colors. Zircon is one of the few colored stones that might show visible dispersion. When you’re showing this gem, look for flashes of rainbow-colored fire and point them out to customers. The supply of zircon is generally limited, and typical sizes depend on color. Blue or green stones normally range from 1 ct. to 10 cts., yellows and oranges up to around 5 cts., while reds and purples are usually smaller. Most colors are available in various fancy shapes, but colorless and blue stones are often fashioned in the style known as the zircon cut—a round brilliant with eight extra facets around the culet. Zircon has medium hardness, and the heat treatment that produces many of its colors might also make zircon brittle. For this reason, it’s safest to recommend zircon in earrings or pendants, or in protected ring settings. This will keep the gem from becoming scratched and abraded and make it less vulnerable to fracturing.

130

Sources Australia Cambodia China Myanmar (Burma) Sri Lanka Thailand Vietnam



Toughness

Fair to good; heat-treated stones can be brittle and might be easily abraded

Stability

Various colors of zircon


Reaction

Heat

High heat can alter color

Light

Generally stable; some heat-treated stones revert to their original color (light brown)

Chemicals

None


Purpose

Stability

Prevalence

Detection

Heat

Produces colorless, blue, yellow, orange, or red from brown material

Generally sta ble, but some stones revert when exposed to light

Routine. Almost all blue or colorless zircons are treated.

Undetectable, but usually assumed due to prevalence

131


Advisability

Ultrasonic cleaning

Risky

Steam cleaning

Risky

Warm, soapy water

Safe

Imitations Cubic zirconia Glass

Blue zircon

Synthetic sapphire Synthetic spinel

Alternatives Almandite garnet Amethyst Aquamarine Chrysoberyl Citrine Demantoid garnet (also shows strong dispersion) Fire opal Hessonite garnet Kunzite Malaya garnet Peridot Pyrope garnet Rhodolite garnet Ruby Sapphire Spessartite garnet Spinel Topaz Brown zircon

132

Tourmaline

Green zircon, Sri Lanka, 5.68 cts.

ACKNOWLEDGMENTS The Gemological Institute of America gratefully acknowledges the following people and organizations for their assistance in providing some of the gems, jewelry, and photography used in this assignment: 23rd St. Shoppe, 43 (top), 77 (bottom), 114, 122, 123 (bottom) A. Ruppenthal KG, 83 (middle) Carol Ackerman, 111 (right) Chris Almquist, 121 (top) Assael International, 75 Bear Essentials, 33 (bottom) Jonte Berlon, 124 Matt Bezak, 117 (bottom) Gordon Bleck, 40, 100, 101 (top left), 102, 107 (bottom), 108, 132 (middle) Gary Bowersox, 13 (bottom), 27 (middle), 54, 55 (top), 57, 132 (bottom left) Buccellati, 74 (bottom left) Alan Caplan, 35 (right) Carolyn Tyler Designs, 2 (bottom) Christie’s Images Inc., 34, 46, 88 Don Clary, 27 (top), 81 (bottom) Cody Opal, 70 Coffin & Trout Jewelers, 125 (top) Colgem Ltd., 98 Creative Jewelers, 2 (top) Crescent Jewelers, 55 (middle), 115 (bottom) Crystal Reflections, 23 Bart Curren, 11 (middle and bottom), 81 (top) Brian Davenport, 87 (top), 91 (left) Anil B. Dholakia, Adris Oriental Gem and Art Corp., 43 (bottom) Dona Dirlam, 81 (top) Ali Farook, 104 Emmanuel Fritsch, 3 (bottom) Fu Gemstone Import, 106 Mary Murphy Hammid, 5 (top and bottom) Herring & J.T. McManus, 12 Herrling-Schmuck, 78 Debbie Hiss-Odell, 39, 90 Hixon Collection, 47 (top) David Humphrey, 19 (bottom), 71 (left), 130 JCK Magazine, 132 (top) J. Grahl Design, 10 (bottom), 11 (top), 37 (top), 72, 73 (bottom), 74 (top), 85, 120, 123 (top) Jim Shaylor Jewelers, 36 (left) Neil Lane, 16 Ledge Studio, 97 (top) Glenn Lehrer, 97 (top) Dave LeRose, 86, 116 (bottom) Andy Lucas, 61 (top) Martin Chung Gemstones and Fine Jewelry Co., 13 (top), 56, 61 (top), 84 (bottom) Mayer & Watt, 5 (top and bottom), 80 Elise Misiorowski, 3 (middle) Ginger Moro, 8, 96, 129 (right) Bernd Munsteiner, 121 (bottom) Natural History Museum of Los Angeles County, 89 (top) Pala International, 99, 125 (middle) Peter Secrest Collection, 17 (top) Smithsonian, 109 (right) Kent Raible, 73 (top) Ramsey Gem Imports, 64 Rigoberto Jewelry Designs, 6, 7, 20, 21, 38, 39 Serengeti West, 125 (bottom) C.Y. Sheng, 26, 27 (bottom) Silverhorn, 4 Michael Stubin, 17 (bottom right) Suzanne Tennenbaum, 29 (top) Tiffany & Co., 13 (middle), 55 (bottom), 110 Van Cleef & Arpels, 88 Harry Winston, 74 (right) Elizabeth Ziegler, 10 (top) Benjamin Zucker, 17 (bottom left) 133

208279795 GIA s Colored Stone Essential s Reference Guide

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