The Three Compulsory Marks
To be a legal UK hallmark, a piece of jewellery must typically feature these three marks:
The Sponsor’s Mark: This indicates the company or person responsible for sending the item to the Assay Office (e.g., the manufacturer or Brufords).
The Fineness Mark: A numerical value indicating the precious metal content (e.g., 750 for 18ct gold, 925 for Sterling silver).
The Assay Office Mark: This tells you which of the four UK offices tested the item (London, Birmingham, Sheffield, or Edinburgh).