UK Hallmark Decoder
Type the number in the hallmark to see the metal and the purity, then match the other marks — assay office, traditional symbol, date letter — with the tables below.
Updated
A number inside a full hallmark was tested by an assay office. The same number stamped alone — common on imported jewellery — is only the maker’s claim.
How to read a hallmark, left to right
- Sponsor’s mark — two to five initials in a shield: the maker, importer or retailer who sent the piece for testing. Compulsory.
- Traditional symbol — a crown, lion, Britannia, orb or Pallas Athena. Optional since 1999, but London still adds it as standard.
- Fineness number — parts per thousand of the precious metal, in a shaped outline. Compulsory since 1999.
- Assay office mark — leopard’s head, anchor, rose or castle. Compulsory.
- Date letter — a letter in a shield for the year of marking. Optional since 1999.
Fineness numbers
| Number | Metal | What it means |
|---|---|---|
| 375 | Gold | 9 carat gold — 37.5% gold |
| 585 | Gold | 14 carat gold — 58.5% gold |
| 750 | Gold | 18 carat gold — 75% gold |
| 916 | Gold | 22 carat gold — 91.6% gold |
| 990 | Gold | 99.0% gold |
| 999 | Gold | Fine gold, often called 24 carat — 99.9% gold |
| 800 | Silver | 80% silver, sometimes called coin silver |
| 925 | Silver | Sterling silver — 92.5% silver |
| 958 | Silver | Britannia silver — 95.8% silver |
| 999 | Silver | Fine silver — 99.9% silver |
| 850 | Platinum | 85% platinum |
| 900 | Platinum | 90% platinum |
| 950 | Platinum | 95% platinum — the usual standard for platinum rings |
| 999 | Platinum | 99.9% platinum |
| 500 | Palladium | 50% palladium |
| 950 | Palladium | 95% palladium |
| 999 | Palladium | 99.9% palladium |
Assay office marks
| Mark | Assay office | Notes |
|---|---|---|
| Leopard’s head | London | Crowned from 1478, uncrowned since 1822 |
| Anchor | Birmingham | Office founded in 1773 |
| Rose | Sheffield | On gold from 1904, on every metal from 1975 |
| Crown (on silver) | Sheffield, before 1975 | Sheffield’s mark on silver until 1975. A crown on gold is the gold standard mark instead |
| Castle | Edinburgh | The Scottish office |
Traditional symbols
| Symbol | Means | Used since |
|---|---|---|
| Crown with a number (18, 22…) | Gold of that carat | 1798 for 18 ct, 1844 for 22 ct |
| Lion passant (walking lion) | Sterling silver hallmarked in England | 1544 (facing the viewer until 1822) |
| Lion rampant (standing lion) | Sterling silver hallmarked in Edinburgh | 1975 |
| Britannia (seated figure) | Britannia silver, 958 | 1697 |
| Orb | Platinum | 2 January 1975 |
| Head of Pallas Athena | Palladium | 2009; hallmarking compulsory from 2010 |
Date letters
The date letter changes every 1 January. When an alphabet is used up, the next one changes font, case and shield, so each letter in its shield belongs to a single year — about every 25 years for the current cycles. Until 1975 each assay office ran its own cycle, so an old letter can only be read with that office’s chart. Since 1975 all four offices use the same letter each year. A new uppercase alphabet began with A in 2025, and 2026 is B. Dating older pieces needs the assay office’s own date-letter charts; the date letter has been optional since 1999, so a modern piece may not have one.
Other marks
| Mark | Means | Dates |
|---|---|---|
| Balance scales | Common Control Mark: a Convention hallmark recognised in every member country | UK from 1975 |
| Sovereign’s head | Duty mark: tax on the piece was paid | 1784–1890 |
| “F” in an oval | Import mark on foreign-made pieces | From 1867 |
| Jubilee or coronation emblem | Commemorative mark, struck for a limited time | 1935, 1953–54, 1977, 1999–2000, 2002, 2012, 2022 |
| +METAL | The piece contains base-metal parts | Current |
When a hallmark isn’t required
UK law requires a hallmark before an item can be described as gold, silver, platinum or palladium — except below these weights: 1 g of gold or palladium, 0.5 g of platinum and 7.78 g of silver. So a light chain or a thin ring may honestly have no hallmark at all.
Stamps that aren’t UK hallmarks
Rings bought abroad usually carry a maker’s stamp instead — 14K, 10K, 18KGP, HGE, PT950 — with no assay office mark. To decode those, use the ring stamp decoder; to put a price on the gold, the gold value calculator. To identify a ring from a photo, try the Ring Identifier, or read the full Ring Guide.
Frequently asked questions
What does 375 mean on a ring?
375 is the UK hallmark for 9 carat gold: 37.5% pure gold, the lowest gold standard in the UK. 585 is 14 carat, 750 is 18 carat and 916 is 22 carat.
How do I tell which assay office hallmarked my jewellery?
Look for the office mark: a leopard’s head is London, an anchor is Birmingham, a rose is Sheffield and a castle is Edinburgh. A crown on silver marked before 1975 is Sheffield too.
How can I date a British hallmark?
By the date letter, if there is one. It changes every 1 January, and its font, case and shield change with each alphabet, so you need the chart for the right office and period. Since 1975 every office uses the same letter each year; a new alphabet began with A in 2025 and B in 2026. The date letter has been optional since 1999.
Does 925 mean real silver?
925 means sterling silver, 92.5% silver. Inside a full UK hallmark it is backed by an independent assay office test. A 925 stamp on its own, with no assay office mark, is only the maker’s claim.
Does jewellery have to be hallmarked in the UK?
To be sold as gold, silver, platinum or palladium, yes — unless it weighs less than 1 g of gold or palladium, 0.5 g of platinum or 7.78 g of silver.
What is the lion on British silver?
A walking lion (lion passant) is the traditional mark for sterling silver hallmarked in England, used since 1544. A standing lion (lion rampant) marks sterling hallmarked in Edinburgh. Both have been optional since 1999.
Sources and further reading
- Hallmarking — The Goldsmiths’ Company
- Hallmarking — The Goldsmiths’ Company Assay Office (London)
- Hallmarking — The Birmingham Assay Office
- Hallmarking: identification — State Library Victoria
- Hallmarking Act 1973 — legislation.gov.uk
Links checked October 19, 2026.