A hallmark is an official mark struck on items made of precious metals. This guarantees the purity or fineness of the metal. Hallmarks are a legal requirement on products of a certain weight, depending on the metal being marked. Silver items below a weight of 7.78g, and gold items below a weight of 1g, do not require hallmarking. In the case of earrings, they are weighted individually; and not as a pair, to determine whether they require hallmarking.

The UK Compulsory Hallmark comprises of three component marks: Sponsor's Mark, Millesimal Fineness Mark and Assay Office Mark.

Hallmarking Example

Example of Compulsory Hallmarks L-R: Sponsor's Mark, Millesimal Fineness, Assay Office


What do the UK hallmarks represent?

Sponsor's or Maker's Mark

This is the registered mark of the company or person that submitted the article for hallmarking. It is formed of initials of that person or company, the shape varies, and a minimum of two initials must be included. Every mark is unique.

Millesimal Fineness Mark

This mark tells you what quality, the metal is, as well as its the metal type. This numerical format was introduced in 1999 and shows the precious metal content of the article, expressed in parts per thousand.

The shape of the surrounding shield indicates metal type. In the Gold Fineness mark, 375 is 9 carat, 585 is 14 carat, 750 is 18 carat and 916 is 22 carat. In the Silver Fineness mark, 925 is Sterling.

Assay office mark

This mark tells you which Assay Office tested and hallmarked the article.

There are four Assay Offices operating in the UK today: London; represented by the leopard’s head, Edinburgh; represented by a three-towered castle, Birmingham; represented by an anchor and Sheffield; represented by the Yorkshire Rose.

View the assay office official guide here