Pure Gold Weight Calculator

In short A piece of jewellery weighs more than the gold in it, and the difference is the alloy that makes it wearable. The pure gold content is simply the gross weight times the karat divided by 24, so one tola of 22K — 11.6638 grams gross — contains 10.692 grams of actual gold and 0.972 grams of copper, silver, zinc or nickel. In troy ounces that is 0.34375, because a tola is 180 troy grains, which is exactly three eighths of a troy ounce. Two things routinely go wrong here. The first is the ounce: gold is priced per TROY ounce of 31.1034768 grams, while a kitchen scale weighs in avoirdupois ounces of 28.349523125 grams, and reading one as the other overstates a holding by 9.7%. The second is choosing between the karat and the hallmark. They are not always the same number — 22K works out to 916.67 fineness but is stamped 916, and 14K works out to 583.33 but is stamped 585 — so on a tola of 22K the two methods differ by about 0.008 grams of gold. A hallmark is a guaranteed minimum rather than a promise of the exact karat, so the stamped figure is the safer one to sell on and the karat figure is the one people mean when they quote a purity.