What a hallmark actually proves
A hallmark is independent evidence. It is not applied by the maker or the shop: it is struck by one of four UK assay offices after the metal has been independently assayed. That is why hallmarks matter when you sell gold — a struck fineness mark tells a buyer the standard the item was certified to, on the authority of an assay office rather than a maker.
Hallmarking in Britain dates back to the 1300s and is often described as the country's oldest form of consumer protection. The modern system is governed by the Hallmarking Act 1973, which makes it an offence to describe an article as gold in the course of trade without the correct marks.
The three compulsory marks
| Mark | What it tells you |
|---|---|
| Sponsor's mark | The registered mark — usually two or three initials in a shaped surround — of the person or company that submitted the article for hallmarking. It identifies the maker, importer or wholesaler, not the assay office. |
| Fineness mark | The precious metal content in parts per thousand, shown inside a shaped surround: 375, 585, 750, 916 or 999 for gold. See our gold purity conversion chart. |
| Assay office mark | Which office assayed and marked the article: a leopard's head for London, an anchor for Birmingham, a rose for Sheffield, a castle for Edinburgh. |
Optional marks you may also see
- Date letter — a letter in a shaped shield showing the year of marking. Compulsory until 1999, optional since.
- Traditional fineness symbol — the pictorial mark for the metal. A crown is used for gold.
- Convention mark — the Common Control Mark used by countries signed up to the International Convention on Hallmarking.
- Commemorative marks — occasional marks struck to mark national events.
When gold does not have to be hallmarked
The Act sets exemption weights. Gold articles weighing under 1 gram are not legally required to carry a hallmark, so very light chains, small studs and thin charms may be solid gold and still unmarked. Bars and coins are outside the system entirely: mints and refiners stamp weight and fineness instead, and government mints guarantee the gold content of their coins.
An unmarked item is not automatically worthless, and a marked item is not automatically what the mark claims. Marks can be worn, foreign, or applied to plated goods. Have the piece out with the rest and it will be looked at.
Hallmarks and stamps are not the same thing
A great deal of jewellery carries a manufacturer's stamp rather than a hallmark. Marks such as "9K", "14K", "GP", "GF", "RGP" or "HGE" are descriptions applied by a maker, and the last four indicate plated or filled items rather than solid gold. A genuine UK hallmark always includes an assay office mark alongside the fineness figure.
Sources
- Hallmarking Act 1973 and the guidance notes published by the UK assay offices.
- The Goldsmiths' Company Assay Office (London), the Birmingham Assay Office, Sheffield Assay Office and Edinburgh Assay Office — the four offices authorised to mark in the UK.
- British Hallmarking Council — statutory oversight of the assay offices.
