Hallmark
Definition
An official mark stamped on precious metal jewelry by an assay office or manufacturer, certifying its metal purity (fineness), origin, and authenticity.
A hallmark is the stamp that tells you what a piece is actually made of. Not what the salesperson said. What an assay office or authorized manufacturer verified. A complete hallmark set typically includes four elements: the fineness mark (metal purity), the maker's mark (who produced it), the assay office mark (who tested it), and sometimes a date letter. Common fineness stamps you'll see: 585 means 14k gold (58.5% pure). 750 is 18k gold. 925 is sterling silver. 950 is platinum. 375 is 9k gold, common in the UK. Reading them takes practice. UK hallmarks are the gold standard for traceability. The Goldsmiths' Company Assay Office in London (along with Birmingham, Edinburgh, and Sheffield) tests each piece and applies marks including the leopard's head, anchor, castle, or rose. European countries use similar systems. France uses an eagle head for 18k and a boar's head for silver. Italy stamps 750 alongside a maker's number registered with the chamber of commerce. In the US, hallmarking is voluntary. Most American jewelry carries a karat stamp (14K, 18K) or fineness number without an assay office mark. That means the manufacturer self-certifies. Reputable brands still stand behind those stamps, but there's no independent verification unless you send the piece to a lab. Why hallmarks matter for value: they confirm melt content for scrap calculations, prove authenticity for resale, and protect buyers from plated or mislabeled goods. I've seen unmarked "gold" chains that tested at 10k or lower. A proper 750 stamp with an assay office mark removes that guesswork. Modern hallmarks are often laser-applied rather than punched, which avoids denting thin wire or hollow pieces.
Usage in the Trade
Hallmarks are found on all precious metal jewelry in countries where hallmarking is mandatory. Jewelers, dealers, and consumers use hallmarks to verify metal purity and manufacturer identity.
Examples
A UK-made 18k gold ring bears four marks inside the shank: a leopard's head (London assay office), "750" (fineness), a maker's initials in a shield, and a date letter "T" indicating 2018. Scrap value on a 5-gram ring at current gold prices runs about $280-$320.
An Italian 925 sterling silver chain stamped "925" with a registered maker number (e.g., "1234 MI" for Milan) confirms sterling purity. Without that stamp, the same chain might be silver-plated brass worth $5 instead of $40-$80.
Frequently asked questions
What does 585 mean on jewelry?
585 means the metal is 14 karat gold, or 58.5% pure gold alloyed with other metals for strength. It's the European fineness stamp equivalent of the US "14K" mark. Common on rings, chains, and bracelets from European and Asian manufacturers.
Is hallmarking required in the United States?
No. US law allows voluntary karat stamping but does not require independent assay office verification. Most American jewelry carries a 14K or 18K stamp without an official hallmark. The UK and most of Europe require mandatory third-party testing.
How do I read UK hallmarks?
Look for four marks inside the shank or on the clasp: the fineness mark (375, 585, 750, or 925), the assay office symbol (leopard for London, anchor for Birmingham, castle for Edinburgh, rose for Sheffield), the maker's mark, and a date letter. All four together confirm the piece was independently tested.