UK hallmarking guide
Hallmarking is one of the oldest forms of consumer protection in the world. In the UK it has been a legal requirement since the 14th century. A hallmark is an independent guarantee of a precious metal article's purity — not a declaration by the seller, but a certification by one of the UK's four assay offices after testing.
The marks
A UK hallmark consists of up to four marks struck into the metal, each conveying specific information about the article.
The registered mark of the maker or company that submitted the article for hallmarking — typically initials within a shaped cartouche. This is the only mark that identifies the maker.
Indicates the type of precious metal and its purity, expressed as parts per thousand (millesimal fineness). A 750 mark on gold, for example, means 750 parts per thousand — 75% pure gold, or 18 carat.
Identifies which of the UK's four assay offices tested and marked the article. All four apply the same standards; the mark records where, not how well, it was tested.
A letter indicating the year of hallmarking. Compulsory until 1999; now optional, but many jewellers still include it. Useful for dating antique and vintage pieces.
The assay offices
The UK has four assay offices, each with its own distinctive mark struck alongside the fineness mark.
The oldest assay office, in continuous operation since 1300. Based at Goldsmiths' Hall in the City of London.
Established in 1773. Now the world's largest assay office by volume, handling around half of all UK hallmarking.
Established in 1457. The only remaining Scottish assay office, having absorbed the Glasgow office in 1964.
Established in 1773 alongside Birmingham. Originally a centre for silver cutlery and plate.
Fineness marks
The fineness mark tells you the metal and its purity. The number is the parts per thousand of pure metal — so 925 silver is 92.5% pure silver.
Yellow, white, and rose gold all use the same fineness marks — the hallmark certifies the gold purity, not the colour. The colour comes from the metals alloyed with the gold: white metals (such as palladium or nickel) for white gold, copper for rose gold. A 750 mark means 18 carat regardless of colour.
| Mark | Metal | Purity | Common name |
|---|---|---|---|
| Gold (yellow, white, and rose) | |||
| 375 | Gold | 37.5% | 9 carat |
| 585 | Gold | 58.5% | 14 carat |
| 750 | Gold | 75% | 18 carat |
| 916 | Gold | 91.6% | 22 carat |
| 999 | Gold | 99.9% | Fine gold |
| Silver | |||
| 925 | Silver | 92.5% | Sterling silver |
| 958 | Silver | 95.8% | Britannia silver |
| 999 | Silver | 99.9% | Fine silver |
| Platinum | |||
| 850 | Platinum | 85% | — |
| 900 | Platinum | 90% | — |
| 950 | Platinum | 95% | Standard jewellery platinum |
| 999 | Platinum | 99.9% | Fine platinum |
| Palladium | |||
| 500 | Palladium | 50% | — |
| 950 | Palladium | 95% | Standard jewellery palladium |
Weight exemptions
Not all precious metal articles require a hallmark. The Hallmarking Act 1973 sets minimum weights below which hallmarking is not required. Small items — very fine chains, thin rings — may fall below these thresholds.
| Metal | Minimum weight requiring hallmark |
|---|---|
| Gold | 1 gram |
| Silver | 7.78 grams |
| Platinum | 0.5 grams |
| Palladium | 1 gram |
Where no hallmark is present, you are relying on the seller's declaration of the metal's purity. For articles above the minimum weight, the absence of a hallmark should raise questions.
Hallmarks from outside the UK
Not all countries operate a mandatory hallmarking system. In the United States, hallmarking is largely voluntary — gold articles may carry a maker's stamp and a carat mark applied by the manufacturer, but these are not independently verified in the way UK hallmarks are. The purity stated is the seller's declaration, not an assay office certification.
Many countries that are signatories to the International Hallmarking Convention use a convention mark — a set of scales within a hexagonal frame — which is legally recognised in all member countries and does not require additional UK hallmarking to be sold here. Member countries include most of Europe.
Beyond the convention mark, many European countries have their own hallmarking systems, some of which predate the convention and remain in use. Some of the most commonly encountered in the UK market:
A star followed by a two- or three-digit number identifies the assay office and fineness. Italy is a major producer of gold jewellery and Italian marks are widely encountered.
The eagle head mark is used for domestic 18ct gold articles; the owl mark appears on imported articles and lower-carat gold. Older French pieces may carry different marks depending on the period of manufacture.
The kokoshnik mark — a profile of a woman in traditional headdress — alongside a fineness number is common on Russian and Soviet-era pieces. Russian gold appears frequently in the pre-owned market.
The crescent and crown mark was used for gold articles until 1888. Modern German hallmarking uses fineness numbers consistent with the convention system.
For vintage or imported pieces carrying unfamiliar marks, a jeweller or independent appraiser can help identify them. Where marks are absent or unclear, a UK assay office can test the metal — and if it meets the required standard, hallmark it.
What to look for
When buying a precious metal article, it is worth taking a moment to check the hallmark:
- —Is a hallmark present? On a significant piece above the minimum weight, its absence should be questioned.
- —Is it legible? Worn or partially struck marks can be difficult to read but should be queried rather than ignored.
- —Does the fineness mark match what the seller describes? A piece described as 18ct gold should carry the 750 mark.
- —Is the assay office mark one of the four UK offices, or a recognised convention mark?
- —On antique or vintage pieces, the date letter can help establish when the article was made — useful for provenance and dating.
