Gold Hallmarks Explained

Millesimal fineness numbers

Most of the world stamps gold with a three-digit number in parts per thousand. The common grades are 333 (8k), 375 (9k), 417 (10k), 585 (14k), 750 (18k), 875 (21k), 916 (22k), 958 (23k) and 999 (24k). A stamp is a legal minimum: a 585 piece must contain at least 58.5 % gold and normally contains exactly that.

Older items may show 583 for 14k — a pre-1980s US and Soviet standard — or 990 for 'chuk kam' Chinese gold. Both are genuine and are priced at their stated purity.

Karat marks

The US and Canada stamp karats instead: 10K, 14K, 18K, sometimes 'KT' or 'KP' (karat plumb, meaning exactly that purity). In the US the legal minimum for anything sold as gold is 10k, and a stamp must be accompanied by a registered trademark of the maker.

A karat is one twenty-fourth: 18k = 18/24 = 75 % gold. Use our gold purity calculator to convert any karat to a percentage and a live price per gram.

Official hallmarking systems by country

United Kingdom: compulsory hallmarking for gold over 1 g. A full UK hallmark shows the sponsor's (maker's) mark, the fineness number in a shaped shield, the assay office mark (leopard's head for London, anchor for Birmingham, rose for Sheffield, castle for Edinburgh) and optionally a date letter.

India: since 2021 hallmarking by the Bureau of Indian Standards (BIS) is mandatory in most districts. The current mark has three parts: the BIS triangle logo, the purity grade (e.g. 22K916, 18K750, 14K585) and a six-character alphanumeric HUID code unique to the item, which you can verify in the BIS CARE app.

European Convention (CCM): members including the UK, Switzerland, Nordic countries and others accept a common control mark — a pair of scales with the fineness number — which is recognised across signatory countries.

Gulf states: the UAE, Saudi Arabia and others require government assay stamps on jewellery; 21k (875) and 22k (916) are the everyday standards, and 18k is common in imported European designs.

Switzerland: the St. Bernard's head mark with the fineness number is the official Swiss hallmark for gold.

Stamps that mean the item is NOT solid gold

GP / GEP: gold plated or gold electroplated — a microscopic layer of gold over base metal. HGE / HGP: heavy gold electroplate. RGP: rolled gold plate. GF / 1/20 12K GF: gold filled — a thicker mechanically bonded layer, but still only about 5 % of the weight. Vermeil: gold over sterling silver.

These pieces have little scrap value. Some refiners buy gold-filled in bulk at a fraction of melt; most pawnshops refuse it.

How to check a hallmark yourself

Use a 10× jeweller's loupe. Genuine stamps are crisp and sit in a logical place — clasp, ring shank, chain tag. Blurry, crooked or oversized stamps on cheap-looking items are a warning sign.

Do a magnet test: gold is not magnetic. A strongly attracted item is plated steel or iron; a non-magnetic item can still be brass, so this only rules things out.

Weigh it. Gold is dense — about 19.3 g/cm³ for 24k, 15.5 for 18k, 13 for 14k. Items that feel too light for their size deserve a professional test.

When in doubt, ask a jeweller to run an XRF test. It is fast, non-destructive and often free if you are considering selling.

Hallmarks on coins and bullion

Bullion bars carry a different set of marks. A cast or minted bar from an LBMA-accredited refiner shows the refiner's logo, the weight (for example 1 oz, 100 g or 1 kg), the fineness (999.9 or 995.0) and, on larger bars, a unique serial number. Many minted bars come sealed in a card with an assay certificate that repeats the serial number. Keep the packaging: it can make resale faster and attract a better buy-back price.

Coins rarely carry a fineness stamp at all; their purity is fixed by law. American Gold Eagles are 22k (916.7) and contain one troy ounce of fine gold despite weighing 33.93 g in total. Krugerrands are also 22k, with copper giving them their orange tone. Canadian Maple Leafs, Austrian Philharmonics and Australian Kangaroos are 999.9. British Sovereigns are 22k and contain 7.32 g of fine gold. Our coin melt value page lists the fine gold content of each major coin.

For both bars and coins, check weight and dimensions against the official specification with a precise scale and calipers. Fakes made of tungsten plated with gold can match weight but usually fail on diameter or thickness, and an XRF or ultrasonic test will expose them.

Why the hallmark matters when you sell

A clear official hallmark speeds up every sale. A buyer who can read 750 next to a recognised assay mark may skip testing or test only lightly, and is more willing to pay a higher share of melt value because the risk of an under-karat piece is lower. Unmarked items are still bought, but expect a test, a lower opening offer and sometimes a refusal from smaller shops. If you own important unmarked pieces, a jeweller can have them assayed and hallmarked for a modest fee before you sell.