This is a stamped mark applied to items of jewellery and silverware by the Assay Offices of Britain as a guarantee of authenticity. The mark consists of four components:

The sponsor (or manufacturer) mark; the standard mark, which denotes the precious metal content of the item; the Assay Office Mark (Assay Offices are found in London, Birmingham, Sheffield and Edinburgh) and the date letter which shows the year in which the article was hallmarked.