Gold is purity marked in several ways, depending on the country in which the gold is handled. Some countries use systems different than that used in the U.S. The 585 mark is part of one of these foreign systems, and it denotes how pure the gold contained within an item is.
Gold is a metal that is malleable and soft in its pure form. Because of these characteristics, gold has to be mixed into an alloy to make its use functional in items such as jewelry. White gold is usually an alloy with palladium or nickel. Yellow gold is an alloy of gold, silver and copper. Rose gold is an alloy of gold and copper. Green gold is an alloy of gold, silver and zinc or cadmium.
European System of Marking
European countries use a system of millesimal fineness to grade the level of purity of gold. The hallmark, assay mark or standard mark on an item is a form of shorthand, stating the quality of the item. Millesimal fineness marks are rounded to three figures. The number 585 refers to the parts per thousand of gold by mass in an alloy. This means an item marked 585 is 58.5 percent gold. If the item is 585 parts gold, 415 parts are made up of another metal or other metals. Gold marked 585 is the equivalent of 14-karat gold in the U.S.
Other Common Marks
Other commonly used fineness marks include 375 for 9-karat gold and 999 to denote 24-karat gold, which is considered pure gold. In the UK, “An article cannot be legally described as being of gold, silver or platinum unless it is hallmarked,” notes the Jewellery Catalogue UK website, unless the item contains less than 1 gram of gold. Hallmarks also include information regarding when and where the metal was tested.
The U.S. Equivalent
In the U.S., you may refer to an item as being 24-karat gold in fineness. Since 24 karat is pure gold, the highest level of fineness, items of lesser karat or gold content are ranked in quality based on how many parts out of 24 are pure gold. For example, 18-karat gold contains 18 karats of pure gold and 6 karats of other metals, notes the Costello’s website. Since 585 gold is equivalent to 14 karat — or carat, as used in many countries outside of the U.S.— this means 585 gold contains 14 karats of pure gold out of a possible 24 total karats and 10 karats of other metals.