In some countries, a national assayer's office controls the testing of silver objects and marking of purity.
Hallmarks are applied with a hammer and punch, a process that leaves sharp edges and spurs of metal.
The hallmark for sterling silver varies from nation to nation, often using distinctive historical symbols, although Dutch and UK Assay offices no longer strike their traditional hallmarks exclusively in their own territories and undertake assay in other countries using marks that are the same as those used domestically.
French silver made for export carries an assay mark in the shape of the head of Mercury, along with a number to indicate the millesimal fineness: "1" for .920, "2" for .840 and "3" for .750.
According to the law, quality-marked silver also must bear the name or a U.S. registered trademark of the company or person that will stand behind the mark.
"[1] Between 1867 and 1933, Austria-Hungary and later, Hungary used the crescent moon crowned head of ancient Greek heroine Diana as the hallmarking symbol of legal silver alloys.
For example, a Diana head within a frame made in the shape of a 5-petal flower represented 5×160/1000 = 800 thousands fineness, a local silver standard commonly used in table forks and spoons.