How this calculator works
The calculator starts from the live 24K gold price per troy ounce, converted to HKD at the current exchange rate. Your weight is converted to grams (1 troy ounce = 31.1034768 g, 1 tola = 11.6638038 g), and the value is adjusted for purity — the multiplier is simply the karat divided by 24, so 22K/916 gold uses 22 ÷ 24 ≈ 0.9167. The formula: value = grams × pure gram price × purity, plus any premium and minus any discount you enter.
Hong Kong jewellery shops sell mostly 足金 (Chuk Kam, "full gold") of 999 fineness — effectively 24K — rather than 22K/916. Chains such as Chow Tai Fook and Chow Sang Sang post a daily gold price and charge workmanship on top.