Gold

Gold jewelry is described in terms of karatage (caratage), as an indication of its gold content. Pure gold is 24 karats, although it is much too soft to be used in jewelry making, which is why fine gold jewelry is so rare. As a rule, gold used in jewelry is an alloy of gold and other metals such as silver and copper.

Various karatages and their equivalent gold content (in percent or in fineness terms) are recognized by international standards. Some popular caratage groups are:

21-22 karats – also marked as 916 or 875 fineness
18 karats – also marked as 750
14 karats – also marked as 585
9 karats – also marked as 375.

Some jewelry, in particular antique pieces, is not hallmarked for its gold content, and may be assayed by a simple method that uses a chemical substance.