Working With Gold.

The materials used by the jeweller fall into two main categories: metallic and non-metallic materials, each having its own important  part to play in jewelry design and construction. From the jewelers point of view, gold and silver are the two most used metals in jewelry.

Once one has worked in gold it is not difficult to see the reason for its popularity and importance. The hardness of pure gold (on moh's scale) is 2-1/2 to 3; the melting point is 2,063 degrees Fahrenheit, specific gravity is 19.32, and tensile strength is 19,000psi. The two attributes of gold which make it an excellent metal in which to work are its malleability and ductility.

Malleability is the property which allows a metal to be rolled and beaten out into extremely fine sheets without cracking, and one troy ounce of pure gold can be beaten out into a sheet of 1/280000 of an inch thick and one hundred feet square.

Ductility is the property which allows a metal to be drawn out into fine wire without snapping, and the same troy ounce of pure gold could be drawn out into a wire fifty miles long.  Indeed gold is the most malleable and ductile of all metals.

Pure gold, which is known as fine gold, is too soft to be of much use to the jeweller since it would wear away too quickly. The jeweller must therefore alloy gold with other metals to produce a harder metal known as a Karat gold alloy. There are many Karat gold alloys which are acceptable for hallmarking by the hallmarking centres or the respective governing authorities.

The most common alloys of gold used in jewellery are:

22 Karat gold, which is an alloy of 22 parts fine gold and 2 parts alloying metal. ( 916 per 1000 parts)
18 Karat gold, which is an alloy of 18 parts fine gold and 6 parts alloying metal. ( 750 per 1000 parts)
14 Karat gold, which is an alloy of 14 parts fine gold and 10 parts alloying metal. ( 583 per 1000 parts)
9 Karat gold, which is an alloy of 9 parts fine gold and 15 parts alloying metal.  ( 375 per 1000 parts)
 
From this we can see that a 'Karat', is a proportion-one-twenty-fourth of the whole. It is different from the 'carat' used when referring to gemstones, when it becomes a weight equivalent to 200 milligrams.

When different alloying metals are used with gold it produces various working properties and various colours in the resulting gold alloys. Red and yellow gold alloys are produced by varying the proportions of copper and silver in the mixture. White gold is produced by alloying with nickel or palladium, while the addition of silver and cadmium to gold will produce a green alloy. For other colours usually one can get  ready made alloys in the market to get the desired colour of gold .

gold information .