Metal that lasts
Hallmark Guide: UK Assay Marks vs US Stamps
The UK assays gold at a legal office and punches 375, 585, 750 plus a town mark. The US mostly trusts a maker’s 14k stamp and the FTC 10k floor. One is a system. The other is a claim.
Updated 27 Aug 2026 · 7 min read · hallmark guide uk vs us
The UK punch is a sentence
A full UK hallmark on a 4 mm band is several marks in a row: sponsor (who sent it), fineness (375, 585, 750, 916, 999), assay office (the animal or object), and often a date letter. That is a government-backed statement that the alloy met the number. Small pieces can carry a simplified mark, but 375 without a sponsor on a heavy ring is incomplete, not “European style.”
Irish harp, Swiss 750, Italian 750 with a maker’s number — other systems, same idea: a number plus a responsible name. Learn the number first. Karat versus 585 is the conversion table.
The US stamp is a claim the FTC polices after the fact
US makers who stamp 14k are saying the alloy is 14k, and the FTC can treat a fake stamp as a problem. There is no Birmingham-style office between the maker and you. Gold-filled should read GF or 14/20, not 14k. Plate should not wear a 14k punch. Fake 14k stamps exist and are often too pretty. XRF still wins.
| Mark | Where | Means |
|---|---|---|
| 375 + assay office | UK | 9k, legally gold there |
| 585 + assay office | UK | 14k |
| 750 + assay office | UK / EU | 18k |
| 14k / 585 | US | Maker claims 14k |
| 10k / 417 | US floor | Legal US gold, paler |
| GF, 14/20 | US | Gold-filled, not solid |
| GP, HGE | US | Plate |
Buying across the ocean
A UK 9k chain with a proper 375 and anchor is real 9k. A US jeweler may still not call it gold at the counter. A US 14k stamp on a chain bought into the UK is usually accepted as 14k if the alloy tests, but it will not have a leopard. Do not add fake UK punches to US gold to “make it look official.” That is forgery. Test the metal, then enjoy the marks as documentation, not as decorations.
Questions, answered
- Is unstamped gold automatically fake?
- No. Old, small, or handmade pieces can lack a stamp. Unstamped plus $29 plus a marketplace stall is the suspicious combination. XRF.
- What is a date letter?
- A UK assay cycle letter that encodes year. Useful for antiques. Irrelevant on a 2026 2 mm chain if the 585 and office mark are present.
- Does platinum use the same offices?
- UK platinum is 950 with its own fineness mark, same offices. US platinum is typically stamped 950 Pt or platinum by the maker, again a claim.
