Look closely inside a gold or platinum ring made in the UK and you will usually find a tiny row of stamped symbols. Together they form a hallmark: an independent guarantee that the metal is at least as pure as it claims to be. Hallmarking is one of the oldest forms of consumer protection in the world, and it is one of the simplest ways to know you are buying genuine precious metal.
Why hallmarking matters
Gold, silver, platinum and palladium are almost always alloyed with other metals to make them strong enough to wear, and you cannot tell the purity just by looking. Under the Hallmarking Act 1973, it is illegal in the UK to describe an item as gold, silver, platinum or palladium unless it has been independently tested and hallmarked by an Assay Office, unless it falls below the legal exemption weight.
The UK Assay Offices
There are four Assay Offices in the UK, and each has its own symbol:
- London – a leopard’s head
- Birmingham – an anchor
- Sheffield – a Yorkshire rose
- Edinburgh – a castle
The three compulsory marks
- Sponsor’s mark – the initials of the company that submitted the item for hallmarking, inside a shield.
- Millesimal fineness mark – the purity of the metal in parts per thousand, inside a shape that identifies the metal.
- Assay Office mark – the symbol of the office that tested and marked the piece.
Common fineness marks
| Fineness mark | Metal | Pure metal content |
|---|---|---|
| 375 | 9ct gold | 37.5% |
| 585 | 14ct gold | 58.5% |
| 750 | 18ct gold | 75.0% |
| 916 | 22ct gold | 91.6% |
| 925 | Sterling silver | 92.5% |
| 950 | Platinum | 95.0% |
Optional marks
You may also see optional marks such as a date letter showing the year of hallmarking, a traditional fineness symbol (for example a crown for gold or a lion passant for sterling silver) or a commemorative mark.
Exemption weights
Very light items do not have to be hallmarked. The exemption weights are 1 gram for gold and palladium, 0.5 grams for platinum and 7.78 grams for silver. This is why some very fine chains or small studs may not carry a hallmark.
Our hallmarking promise
Every qualifying piece we make in our Hatton Garden workshop is independently tested and hallmarked by a UK Assay Office before it is sent to you. Browse our engagement rings and wedding rings, read our metal guide, or visit our showroom and we will show you a hallmark under a loupe.