Guide · 4 min read · updated 22 Oct 2026
UK gold hallmarks explained
How to read the marks on your jewellery and tell 9ct from 18ct in seconds.
A UK hallmark is a set of small stamps proving an item has been independently tested. It tells you who made it, how pure it is and where it was tested.
The marks
- Sponsor's mark — the initials of the maker or importer.
- Fineness mark — the purity in parts per thousand.
- Assay office mark — London (leopard's head), Birmingham (anchor), Sheffield (rose) or Edinburgh (castle).
- Date letter — optional since 1999, but common.
Fineness numbers for gold
| Mark | Carat | Gold content |
|---|---|---|
| 375 | 9ct | 37.5% |
| 585 | 14ct | 58.5% |
| 750 | 18ct | 75% |
| 916 | 22ct | 91.6% |
| 999 | 24ct | 99.9% |
No hallmark?
Items under 1g, foreign jewellery and older pieces are often unmarked. That doesn't mean they're not gold — we test them for free with XRF, which doesn't damage the item.
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