Basic Knowledge of Gold THE CHEMICAL SYMBOL of gold is AU from Aurum, the Latin word for gold. Chemically gold is an element, which means it cannot be broken down further. Pure gold (24 carat) is soft and easily damaged so it is not often used in jewelry today. To make gold more practical it is alloyed with different metals, like copper, silver and zinc, to give it strength and durability. Different proportions of these alloys are what makes the different shades of gold red, or rose gold, white gold, green gold or yellow gold. Pure gold is yellow in color. Nevertheless, the color changes depending on the added alloy metals, as illustrated below: YELLOW GOLD- GOLD ,COPPER ,SILVER WHITE GOLD- GOLD, NICKEL, ZINC, SILVER, PLATINUM GREEN GOLD- GOLD, SILVER, COPPER ZINC RED GOLD- COPPER, GOLD Karat grade is used to express the purity of gold. It basically refers to the proportion of gold in an alloy. Pure gold (100 per cent) is 24 karat. The proportions in other karat are as in the table below.
KARAT
PART GOLD TO ALLOY
PERCENTAGE
FINENESS
416
10kt
10/24
41.66%
14kt
14/24
58.33%
583
18kt
18/24
75%
750
22kt
22/24
91.66%
916
24kt
24/24
100%
1000
Example: 22K means that 22 out of 24 portions are gold. This equals 91.66 per cent of gold, hence it is also known as 916 gold. Similarly 18K contains 75 per cent gold. Here are few facts about gold:
As an element, gold cannot be further broken down by chemical means. Hence it is indestructible and permanent.
Gold is also such an inactive metal that it is not affected by air and water, i.e. does not oxidize (tarnish, rust or corrode).
Gold is highly malleable (i.e. the ability to be pound into thin sheets) such that a single ounce of gold can be hammered into a 100 squarefoot sheet.
Gold reflects infrared rays while allowing sunlight to pass through, hence its use in astronaut helmets and window glass.
Gold is most ductile (ability to draw out into wire) that a single ounce of it can be drawn out into a 50mile long wire!
South Africa is the largest gold producing country in the world. Other leading producers include Russia, Canada, and the United States.
Gold is so heavy that one cubic foot of it weighs half a ton.
Basic information about Silver
Silver --- is one of the precious metal after gold. Silver prices no less real high than platinum or gold, but silver is too soft and easily deformed, so usually Other alloys are added to increase hardness.Different countries to add the alloy are different, as the international standard, silver content of more than 1000 per 925 identified as 925 silver. The melting point of silver is 961.93°C, boiling point is 2212°C, specific gravity is 10.50 (20°C), with a valence of 1 or 2. Pure silver has a brilliant white metallic luster. Silver is slightly harder than gold. It is very ductile and malleable, exceeded in these properties by gold and palladium. Pure silver has the highest electrical and thermal conductivity of all metals. Silver possesses the lowest contact resistance of all metals. Silver is stable in pure air and water, although it tarnishes upon exposure to ozone, hydrogen sulfide, or air containing sulfur.
Uses: The alloys of silver have many commercial uses. Sterling silver (92.5% silver, with copper or other metals) is used for silverware and jewelry. Silver is used in photography, dental compounds, solder, brazing, electrical contacts, batteries, mirrors, and printed circuits. Freshly deposited silver is is the best known reflector of visible light, but it rapidly tarnishes and loses its reflectance.
Silver possesses, it's working qualities similar to gold but can achieve the most brilliant polish of any metal. To make it durable for jewelry, however, pure silver (999 fineness) is often alloyed with small quantities of copper. In many countries, Sterling Silver (92.5% silver, 7.5% copper) is the standard for Jewelry and has been since the 14th century.
The copper toughens the silver and makes it possible to use silver 925 for decorative and fashionable jewelry.
Jewelry Manufacturing Process
Jewelry manufacturing process • Jewelry manufacturing process includes most advance technologies and dedicated research. Jewelry making is a very composite process undergoing a long and slow procedure making it tough from the initial point to the concluding point. Each product undergoes a series of procedures before we get the net product as a beautiful jewelry product.• The natural components of jewelry (stones, metals, and accessories) will undergo multiple processes. These jewelries are unique and involve a lot of time and
skill. Except for personalized jewelry which are handcrafted, most of the jewelries are executed by casting machines. Following is a brief description of all the processes involve in the manufacturing chain. In order to produce a unique piece, theDesign Making very initial step is to create a design, this is the point from where the magic begins! An idea of the end product by very talented designers who then makes a sketch of the design. This process of Blueprint Designing is carried out by proficient craftsmen using techniques and methods handed down over decades. • Each piece of jewelry starts off with a concept. A concept is basically a rough design in the mind of the designer. The final design is the result of close cooperation between designer and craftsman giving the art object a real hand crafted origin. The designers concept and drawings are used by the Model maker to create the original piece of Jewelry. Once the master piece of jewelry is complete, it is used to make a high technology mold, which in turn is usedMolding to make wax reproductions of the Jewelry. • After the sketch is complete with all the fine details, it is passed on to the molding section. In the molding department the very experienced professional molders then turn the sketch into a master mold which sets the base for the total process there from. The master mold is a very complex level of crafting as the final outcome rests on the master mold. Casting again is a very complex process and requires utmostCasting skilled and experienced casters for the desired final product. The wax replicas are placed in steel containers which are then occupied with investment powder and the containers are heated in a chamber to 550°C which solidifies the powder and melts the wax leaving behind a perfect effect. Liquefied metal is then poured into the flasks, allowed to cool, then demolished to reveal the jewelry in casting form. Filing is an essential technique in jewelry making ,Filing and although simple in concept following proven practices combined with the right equipment and tools, ensures the job becomes a breeze. • Filing Precious Metals Filing is used in jewelry making to remove excess metal, even out surfaces, smooth or to shape, form and texture pieces. Every part must be polished while the mount is being made. The entire mount is carefully made Polishing clean and polished to a the highest degree of smoothness so that each and every part is attractively polished off. After stage setting, the polisher is credit worthy for giving the jewelry a concluding polish. All tinctures of the polishing compounds and rouge must be meticulously got rid of either by careful washing by hand, or by use of supersonic cleaning baths. After the product has passed from the polishing and finishing departments, it has Embellishments/ to undergo for embellishment process. Decorative processes When the products gets casted and foiled, the required decorative stones of the correct sizes and weight are cut and made with extreme preciseness and are then assorted for the final setting which is done once the products leave the
foiling and finishing department. • It requires immense patience and skill to make the master-model and to produce a exquisitely casting free from defects and which needs the minimum of chasing to make it perfect. Applied wire, which may be drawn or stamped out, can also be, classified as inherent decoration. Once the casting process is Finishing over and the caster delivered the products to the following department, they are then foiled extreme attention for a smooth and soft finish. These castings are then hand finished in order meet to high standards - adding adjustments and settings before being delivered to all corners across the world. Considerable technical improvements have been made in plating, especially as used in the Plating jewelry trade. Most plating is done by electro- deposition, rhodium, copper, chro mium or other metals being practiced by passing an electric current through a solution and then channelizing the plating metal from the piece of pure metal to the object set aside in the solution. Deliberate attention must be paid to fabricating and polishing procedures because it is vitally significant that consumes to be plated should be perfectly finished in advance. After the plating process is over, the product is Quality Checking brought to the checking department where each and every piece is checked with excessive attention and thoroughly checked for any defects. This process of quality checking is done by very experienced workers and all the defected pieces are send back to the respective departments. Last but not the least, once all Transporting and the products pass through all the Packaging inspections and checking, it is then forwarded for final packaging and labeling. Each product is extensively packed into respective boxes in order to avoid any sort of damages. • Thus, each piece of jewelry, regardless of its size and weight, passes through a long and complex manufacturing process forming each piece as valuable, worthful and unique as the process it tolerates.
