Pure gold (24K) weighs 480 grains per ounce on the Troy scale (used for measuring precious metals and gems. 1 gram = 15.04323583529 grains. 30 grams X 15.04323583529 grains divided by 480 grains = .964522397056 ounces Troy of pure gold )24K). 1 ounce Troy of pure gold = approximately 31.1 grams. For lower weights, 14K, 18K, etc. Divide that number by 24 then multiply times final answer. For example: .964522397056 ounces of 14K gold would only be .56263806495 ounces of pure gold.