Where to find the hallmark
Hallmarks are usually tiny, so use a jeweler's loupe or your phone camera's zoom. On rings, look inside the band. On chains and bracelets, check the clasp, the jump ring next to it or a small flat tag. On earrings, look at the post or the back of the hook. On pendants, check the bail where the chain passes through. Coins and bars state their weight and fineness on the face, and bars from recognised refiners also carry a serial number.
Purity numbers and what they mean
Most of the world now uses millesimal fineness, a number out of 1,000. The common gold marks are 375 (9k), 417 (10k), 585 or 583 (14k), 750 (18k), 875 (21k), 916 (22k), 958 (23k) and 990 or 999 (24k). In the United States, karat marks such as 10K, 14K and 18K are more common than numbers. Our karat purity guide explains the maths behind each grade.
Country systems you will come across
Not every country hallmarks gold the same way, and knowing the system tells you how much to trust a mark.
- United Kingdom: legally required hallmarks from one of four assay offices (London, Birmingham, Sheffield, Edinburgh). A full mark has a sponsor's mark, a fineness number in a shaped shield, an assay office symbol and an optional date letter.
- European Union and Convention countries: the Common Control Mark, a balance-scale symbol with the fineness number, is recognised across member states of the Hallmarking Convention.
- India: BIS hallmarking is mandatory for most jewelry. A modern BIS mark shows the BIS logo, the purity grade (for example 22K916) and a six-digit alphanumeric HUID code that can be verified in the official BIS Care app.
- Gulf states: jewelry is commonly marked 18, 21 or 22 with a national assay stamp. In the UAE, Saudi Arabia and Egypt, 21k (875) is the everyday grade.
- United States: there is no government assay office. Karat marks must be accurate within legal tolerance and must be accompanied by a registered trademark of the maker, but enforcement is lighter than in the UK or India.
- Turkey: jewelry is generally stamped 14 ayar (585), 18 ayar (750) or 22 ayar (916), and coins such as the Çeyrek are 22k.
Marks that mean 'not solid gold'
These marks are the most important ones to know, because they tell you an item has little or no scrap value:
- GP, GEP or GE: gold plated or gold electroplated, a microscopic layer of gold over base metal.
- HGE or HGP: heavy gold electroplate. Still a thin layer.
- RGP: rolled gold plate, a thin sheet of gold bonded to base metal.
- GF or 1/20 12K GF: gold filled. Contains more gold than plating (often 5% by weight) but far less than solid gold. Some refiners buy gold-filled scrap at a low rate.
- Vermeil: gold plating over sterling silver. The silver has some value; the gold layer adds little.
- 18KGP or 14K HGE: a karat number followed by a plating mark still means plated, not solid.
Quick checks at home
None of these replaces a professional test, but they filter out obvious fakes. First, use a strong magnet: gold, silver and platinum are not magnetic, so if the item jumps to the magnet it is not solid gold (the clasp spring may be steel, so test the body). Second, look for wear: on plated items, the base metal often shows through at edges, clasps and the inside of rings as a different colour. Third, check the weight: gold is very dense, so a large but very light piece is suspicious. Avoid scratch and bite tests, which damage the piece and prove little.
Professional testing
A reputable buyer should test unmarked or doubtful items in front of you. Acid testing on a touchstone is quick and cheap. Electronic testers measure conductivity. XRF analysers are the gold standard: they read the composition of the surface in seconds without damage. Fire assay is the most accurate of all but destroys a small sample, so it is used for large refining lots rather than individual jewelry. If a buyer claims your 18k-stamped item is only 14k, ask them to show you the test result.
Fake hallmarks
Hallmarks can be faked, especially on items sold online or abroad. Warning signs include a mark that looks blurry or uneven, a purity number on an item that is clearly magnetic, or a well-known brand stamp on a piece priced far below the value of its gold. For valuable items, a test is always worth more than the stamp.
Turning a hallmark into a value
Once you know the karat, the value is a straightforward calculation from the weight and today's price. Look up the matching page, for example 9k gold, 14k gold, 18k gold or 22k gold, and enter the weight into the calculator. For several items with different marks, the scrap gold calculator adds them all up. When you are ready to sell, read our guide to selling gold.