White gold is an alloy of pure gold made by adding nickel or palladium to pure gold. Nickel and palladium give the white finish and sometimes Rhodium is used in place of Palladium.
The purity of gold has always been defined by the term karat, which is 1/24 part of pure gold by weight. Pure gold is equivalent to 24k. In Europe gold purity is described by by its fineness, which is the amount of pure gold in parts per 1000. For example, a gold coin containing 583 fine gold has 583 parts (58.3%) gold and 417 parts (41.7%) of other base metals.
Products with White Gold
Due to the softness of pure (24k) gold, it is usually alloyed with base metals for use in jewelry, altering its hardness, ductility, melting point and color. Alloys with lower purity (22k, 18k, 14k or 10k) contain higher percentages of copper, or other base metals or silver or palladium in the alloy. Using copper as the base metal most common.
In the United States FTC rules require that all jewelry items sold as gold be described by "a correct designation of the karat fineness of the alloy". No jewelry item less than 10k may be sold in the United States as gold jewelry.
Parts Gold: 18/24
Gold percentage: 75%
USA markings: 18k
European Markings: 750
White gold is usually coated with Rhodium to provide the true white finish.
