To ensure that items pass assay, the alloy used by the goldsmith will be slightly finer than the absolute minimum standard.
This is not shown by the hallmark, which records only that the item passed assay and was therefore of at least the required fineness.
From 1 June 1907 Swiss hallmarks are rarely seen on imported watches; British import hallmarks appear instead, sometimes alongside Swiss hallmarks. This means that 0.75, three quarters, of the weight is gold, the rest is base metal.
British import hallmarks, like all British hallmarks since 1478, do include a date letter. This means the minimum proportion of precious metal (gold, silver, etc.) in the alloy. The alloy must assay at this standard in order to qualify to be hallmarked.
Contents Swiss Hallmarks Poinçons de Maître Precious Metals Act 1880 Swiss Gold Standards • Eighteen Carat Gold • Fourteen Carat Gold • Nine Carat Gold • Twelve Carat Gold Swiss Silver Standards • 0.875 Silver • 0.800 Silver Additional Silver Grades • 0.900 Silver • 0.935 Silver • 0.925 Silver Platinum The Merchandise Marks Act • Three Bears: 935 silver • Three Heads: 0.755 gold • 9 and 12 Carat Gold • "Swiss Made" Plaqué Or - Gold Plated Precious Metals Act 1933 Déposé No. Regulations were later introduced in the cantons of Neuchâtel and Schaffhausen, each having its own standards for gold and silver, its own system of testing and hallmarking, and its own unique set of marks.
British hallmarks at the time did not contain a number indicating a percentage or millesimal fineness, the mark for 18 carat gold was a crown and the number 18.Different expressions of the same number are often seen, e.g.