Hallmark is the declaration to the purity and fineness of the precious metal. A hallmark indicates that an article has been independently tested at an Assay Office and guarantees its conformity to the legal standards of precious metal contents. There are three essential hallmarks applied to precious metals as a quality control: a sponsor's (maker's) mark, a fineness mark, and an assay office mark. These marks establish the origin and fineness of the precious metal and ensure it has been accurately and independently tested.
There are few exemptions to the hallmarking laws. One exemption is by weight; compulsory hallmarks are not needed on gold under 1g, silver under 7.78g and platinum under 0.5g. Also, the UK is required by the European Court of Justice to accept other European national hallmarks as sufficient hallmarking, providing those hallmarks represent an equivalent guarantee of quality.