Hallmarks are the result of having an assay test by one of the four UK assay offices. To "assay" is to test and assess the precious metal content of an item. The four UK assay offices are London, Birmingham, Sheffield and Scotland. Hallmarking jewellery is governed by las and covered under the "1973 Hallmarking Act"

Each office has an individual mark denoting the assay office, a panthers head for London, a anchor for Birmingham, a Yorkshire Rose for Sheffield and Edinburgh Castle for Scotland.

 



The hallmark will generally show a makers mark, the finesse (carat value), the assay office stamp  and a date year stamp.

This illustration shows both types of hallmark for the purity with the numbers in a square or with the scales.

There are two ways of adding the hallmark to a piece of jewellery.

Punching

Traditionally, the hallmarks are 'struck' using steel punches. Punches are made in different sizes, suitable for tiny pieces of jewelry to large silver platters. Punches are made in straight shank or ring shank, the former for normal punching with a hammer, and the later used with a press to mark rings. The problem with traditional punching is that the process of punching displaces metal, causing some distortion of the article being marked. This means that re-finishing of the article is required after hallmarking.