Understanding Gold Purity: Karats, Fineness and Hallmarks
What 24K, 22K and 999 fineness actually mean, and how to read the marks on a bar or coin.
Gold purity is expressed in two common ways. The karat system divides purity into 24 parts, so 24K is essentially pure gold while 22K contains 22 parts gold and 2 parts other metals. Fineness expresses the same idea in parts per thousand: 999 means 99.9% gold, and 916 corresponds to 22K.
Investment-grade bars and coins are usually 999 or 999.9 fine. Jewellery is commonly 22K or 18K because pure gold is soft and other metals add strength.
Marks on a bar normally show the refiner, the weight, the fineness and a serial number. Always match these against the documents supplied with the product and, where you can, against the refiner's own records.
Before any purchase, ask for the fineness in writing, the weight, the refiner or source, and how the item will be tested or verified at handover.