Gold purity may also be described by its fineness, which is the amount of pure gold in parts per 1000. For example, a gold ring containing 583 fine gold has 583 parts (58.3%) gold and 417 parts (41.7%) of other base metals.
Federal Trade Commission rules require that all jewelry items sold in the United States as gold shall be described by “a correct designation of the karat fineness of the alloy.”