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26Feb

Gold jewellery industry terms of reference

Jewellery Jargon

When it comes gold jewellery there are a lot of technical terms that may not be as clear to you as they are to jeweller. Here is a list of general terms that are used by jewellers that will give you a better perspective about jewellery.

Karats

The term karat is a measurement system used by jewellers to establish the purity level of gold in jewellery pieces. The karat system is based on a 24 part scale which means 24 Karats = 100 % and hence 12 Karats would mean 50 % based on the calculation 12/24 x 100% = 50 %. Now that this has been explained as an example if a gold necklace is said to be 18 Karats gold and weighs 50 grams for instance, the total gold content in that necklace can be calculated as 18/24 x 50 grams which would be equivalent to 37.5 grams. The total amount of gold contained in that necklace is only 37.5 grams, the remainder 12.5 grams is probably some other metal that could range from copper to zinc or silver.

24 Karat: 99.9% Pure
22 Karat: 91.7% Pure
18 Karat: 75% Pure
14 Karat: 58.3% Pure
12 Karat: 50% Pure
10 Karat: 41.7% Pure

Alloys

Alloys are basically combinations of metals and most gold jewellery is alloyed in order to harden them as pure gold is too soft to turn into jewellery pieces.

Annealing

When jewellers work with metals and repeatedly subject them to press pressures, they become brittle and thus they ‘anneal’ the metal by heating and cooling the work piece in order to restore its malleability and ductility before continuing work on it.

Assaying

Assaying is a term used for testing the purity levels of alloys containing gold in order to determine its karat and affording the jewellery piece an appropriate hallmark.

Fineness

Fineness is a bit like karat with the only difference being it relates to the proportion of silver or gold in a given metal alloy which is expressed in parts/ thousand. For instance the fineness of sterling silver is .925.

Hallmark

This is an indication of ‘who’ the maker or manufacturer of a jewellery piece is, and the content of precious metal in a jewellery piece.

Rolled Gold

A process that was invented in the 19th century which involves a thin gold sheet laminated unto brass and heated in order to fuse them together. The alloy is then used to make jewellery which wears well and is durable despite the low content of gold in it.

Yellow Gold

Gold that contains a mixture of both copper and silver in equal parts.

White Gold

White gold jewellery is made from a combination of pure gold and white metals which include zinc, nickel, platinum and silver. However, white gold jewellery is known for being brittle despite it being durable and highly resistant to tarnish, to overcome the brittleness, jewellers use platinum or rhodium plating.

Rose Gold

Rose gold jewellery are alloys that contain gold and copper at a ratio of 3:1 in general. However, this ratio is at times adjusted by the jeweller to attain a different ‘tint’ for the jewellery item.

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