The number 585 is stamped on European gold jewelry to indicate that the jewelry contains 58.5 percent gold. This is comparable to the U.S. 14K marking that indicates that a piece contains 14 parts gold and 10 parts of one or more different metals, which means that it is 58.3 percent gold.
Pure gold is soft, so it is not durable when used by itself. Combining gold with other metals increases its strength, alters its color and makes it more affordable. European gold jewelry stamped with the number 750 indicates that the piece is 75 percent gold, comparable to an 18K marking on a U.S. piece, while the number 417 stamped on a European gold piece means that it is 41.7 percent gold, similar to a 10K U.S. marking.