Pure gold is a malleable material and cannot be used alone for the realization of jewels. This is the reason why is always associated with other materials that give the necessary toughness. These materials associated are called alloys. The word Alley has the following definition: An alloy is a mixture of metals or a mixture of a metal and another element, defined by a metallic bonding character. Both gold and silver can be found in different carats, which are different combinations of gold or silver with other materials of less value and price. Carats define the percentage of pure gold inside the jewel in analysis.

The following chart shows the relationship between carats and millimeters.

24 Kt > 24 carats > 999/1000 g of total alloy

22 Kt > 22 carats > 916,66/1000 g of total alloy

21,6 Kt > 21,6 carats > 900/1000 g of total alloy

18 Kt > 18 carats > 750/1000 g of total alloy

14 Kt > 14 carats > 333/1000 g of total alloy