The metal is tested and marked at special offices, regulated by the government, known as assay offices.
Only metal of the required standard will be marked.
The hallmark for sterling silver varies from nation to nation, often using distinctive historic 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.
One of the most highly structured hallmarking systems in the world is that of the United Kingdom, (Scotland, England, Wales and Northern Ireland), and Ireland.
Marks indicate it is Britannia gauge silver made by (or for) Paul de Lamerie (taken to or) in London and dated 1732 (it could have been made a year or two earlier than 1732).
The French assay mark for sterling silver is the head of the goddess Minerva.
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.
French silver also is punched with the mark of the maker.
While American manufacturers did not apply assay marks, city marks or date marks, they did apply a maker's mark. The old hallmarks were as unique as today's logos, and disputes often arose when one company copied another's stamp.
Since these could vary considerably in purity, from around .750 millesimal fineness to around .900, silver known as "coin silver" varies in purity.
Silver at that time was sometimes marked "COIN" or "PURE COIN", but can also be without a standard mark altogether.
"In the USA, The National Gold and Silver Marketing Act does not require precious metals to be marked with quality.
However, if a quality mark is used, the mark must be accompanied by a manufacturer's hallmark that is a registered trademark or the name of the manufacturer.