An assay office is an official body that tests the purity of precious metal articles and, if they meet the legal standard, stamps them with hallmarks. In Britain, silver, gold, platinum and palladium items above certain weights must be hallmarked before they can be sold as such.
Hallmarking in England dates back to a statute of 1300, and the London assay office at Goldsmiths' Hall gave the word hallmark its name. Over the centuries assay offices operated in many cities, including York, Newcastle, Norwich, Exeter, Chester, Edinburgh, Glasgow and Dublin, while Birmingham and Sheffield were established in 1773 to serve their growing metalworking trades. Today the offices still working in the United Kingdom are London, Birmingham, Sheffield and Edinburgh. Each office has its own town mark, such as the leopard's head for London, the anchor for Birmingham, the crown and later the rose for Sheffield, and the castle for Edinburgh. Identifying the assay office, together with the maker's mark, standard mark and date letter, allows a collector to establish where and when a piece of silver was made, and marks from offices that closed long ago are of particular interest.
