All watch cases made of gold, silver, platinum or palladium, of foreign or domestic manufacture, sold in Switzerland, are subject to inspection and compulsory official marking. A single official hallmark is used for all precious metals and all fineness standards, the head of a St. Bernhard dog.
Some 40 specialists - sworn assayers - carry out industrial police duties at the Office for Precious Metal Control in Bern and in five Assay Offices. They check the authenticity of the precious metals produced in Switzerland and those imported into the country, thereby protecting consumers from counterfeits and manufacturers from unfair competition. Each year more than 1 million items are given the official hallmark. Controls uncover well over 2,000 cases of counterfeit goods or false information every year.During touchstone testing, the item under test is compared with a reference alloy. The marks left on the touchstone are brushed with an acid, which is then absorbed by blotting paper. Differences in purity are clearly visible to an experienced assayer. For an accurate analysis, the precious metal sample under test is first weighed and then cupelled. The purity of a precious metal item can also be assessed using X-ray fluorescence.