The three compulsory marks on a UK hallmark
Under the Hallmarking Act 1973, a business that describes an item as gold must have it hallmarked unless it weighs under 1 gram or another exemption applies. The duty sits with the business, not the private owner: selling your own unhallmarked jewellery is legal. A UK hallmark has three compulsory marks and may carry optional marks beside them:
- Sponsor’s mark: two to five initials inside a shield, registered by the company or person that sent the item for hallmarking. It is not always the maker.
- Fineness mark: the precious metal content in parts per thousand, such as 375 for 9ct or 750 for 18ct. The shape around the number shows the metal: for gold, a rectangle with its corners cut off; for silver, an oval.
- Assay office mark: the town mark of the UK assay office that tested and marked the item: a leopard’s head for London, an anchor for Birmingham, a rose for Sheffield, a castle for Edinburgh.
The optional marks are a date letter, which changes on 1 January each year, a traditional fineness symbol (the crown, on gold) and, in some years, a commemorative mark. The date letter and the traditional symbols have been optional since 1999, so a modern piece may not show them.
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UK gold fineness marks
| Carat | Fineness mark | Gold content | Optional traditional symbol |
|---|---|---|---|
| 9ct | 375 | 37.5% | Crown (optional since 1999) |
| 14ct | 585 | 58.5% | Crown (optional since 1999) |
| 18ct | 750 | 75.0% | Crown (optional since 1999) |
| 22ct | 916 | 91.6% | Crown (optional since 1999) |
| 990 gold | 990 | 99.0% | Crown (optional since 1999) |
| 24ct | 999 | 99.9% | Crown (optional since 1999) |
Any other number on gold, such as 333, 417, 575 or 583, is a foreign standard, a maker’s own stamp or a misreading, not a UK hallmark. The gold hallmark guide explains those stamps, and every piece GoldPaid buys is XRF-tested whatever it is stamped.
The four UK assay offices
- London Assay Office (Goldsmiths’ Hall): a leopard’s head. Leopard’s head marking dates from a statute of 1300; the permanent assay office at Goldsmiths’ Hall dates from 1478.
- Birmingham Assay Office: an anchor. The office opened in 1773 under the Act of Parliament that also created the Sheffield office, after a joint petition from the two towns.
- Sheffield Assay Office: a rose. Sheffield used a crown for silver from 1773 until the end of 1974; the rose, used on gold since 1904, replaced it on silver from 1 January 1975 under the 1973 Hallmarking Act.
- Edinburgh Assay Office: a castle. Parliament set standards for gold and silver work throughout Scotland in an Act of 1457, and Edinburgh dates its hallmarking to that year.
Marks from assay offices that have closed, such as Chester or Glasgow, appear on older pieces. Check those against the assay offices’ own historic resources.
Sources
- Hallmarking: practical guidance, summary and guidance notes (PDF), GOV.UK, updated 30 December 2022.
- Hallmarking Act 1973, Schedule 1 (exemptions), legislation.gov.uk.
- What is a hallmark? and History of hallmarking, Goldsmiths’ Company Assay Office.
- UK hallmarks and history, Sheffield Assay Office.
- The early history, Edinburgh Assay Office.
- Checked 11 September 2026. GoldPaid buys gold and silver by post, so it has a commercial interest in precious metal.
Common questions
Can gold be sold by post in the UK if the hallmark is worn away?
Yes. Every item is tested by non-destructive X-ray fluorescence (XRF). Worn flat, never struck, or lost when a ring was resized: it makes no difference, because the analyser reads the metal itself rather than the mark.
What does a 375 stamp mean on a ring?
A 375 stamp means 9ct gold: 375 parts in every 1,000 (37.5%) are pure gold. The rest is other metals, usually silver and copper. On a UK hallmark the 375 sits in a rectangle with cut corners, beside the sponsor’s mark and an assay office mark.
Why is there no crown on my modern gold hallmark?
Because the crown has been optional since 1999. A modern UK gold hallmark can show only the sponsor’s mark, the fineness number and the assay office mark. The Goldsmiths’ Company Assay Office in London still applies the traditional symbol as standard, so some modern pieces do carry it.
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