Gold Purity API
Gold purity and karat maths as an API, computed locally and deterministically — the karat, fineness and alloy numbers a jeweller, goldsmith, assayer or refiner works to. The karat-to-fineness endpoint converts between the two purity systems: karat is the number of 24ths of a piece that is pure gold, so the fineness (parts per thousand, the figure on a hallmark stamp) = karat ÷ 24 × 1000 and the gold percentage = karat ÷ 24 × 100 — 24K is pure (1000‰), 18K is 750‰ (75 %), 14K is 583‰, 9K is 375‰. The pure-gold-weight endpoint gives the actual fine gold in a piece = its total weight × the gold fraction (karat ÷ 24): a 10 g 18K ring holds 7.5 g of gold and 2.5 g of alloy, the fine-gold content a refiner pays on and the basis of the intrinsic metal value. The alloy-mix endpoint inverts it for the bench: to bring refined fine gold down to a target karat, the total weight = the fine gold ÷ (target karat ÷ 24) and the alloy to add = the total − the fine gold, so 7.5 g of pure gold makes 10 g of 18K with 2.5 g of master alloy. Everything is computed locally and deterministically, so it is instant and private. Ideal for jewellery and goldsmithing tools, pawn and scrap-gold apps, and assay and metal-value calculators. Pure local computation — no key, no third-party service, instant. Purity maths only — it does not fetch the live gold price. 3 compute endpoints. For a metal part's weight from its dimensions use a metal-weight API.
api.oanor.com/goldpurity-api
