In Britain gold or silver watch cases, wherever they were made, should always have been assayed and hallmarked in a British assay office before sale.
British laws on hallmarking were enacted long before watches were even invented!
This page isn't an end in itself, it is intended to help make a start on identifying the hallmarks in your watch case and then lead you to another page with more detail.
On this page there is a brief description of a number of different types of hallmarks that you are likely to find in a watch case, and then for the British and Swiss marks there are links to take you to the full page of information for that type of mark.
This page is principally about legally mandated and regulated hallmarks found on gold and silver English and Swiss watch cases.
In Europe assay and hallmarking was, and still is, a legally required process of checking and the fineness of an item and then stamping it with control marks that show the results.
Gold and silver watch cases submitted for hallmarking at a British assay office had first to be stamped with a identification mark registered at the assay office in question, and from this the identity of the person or company who submitted the item can be established.
Swiss watch cases were required to be assayed and hallmarked from 1880.
Swiss gold and silver watch cases were not hallmarked in Switzerland until hallmarks for watch cases were introduced by law in 1880.
Before that date gold cases were usually stamped with their carat fineness by the case maker, and silver was marked with its millesimal fineness, usually 800, or sometimes just "fine silver".
For instance the London Assay Office town mark for watch cases manufactured in Britain was a leopard's head, but the town mark used on imported watches became the zodiac symbol Leo on a crossed back ground in an oval shield.
An easy way to distinguish a British hallmark struck on an imported watch case after 1 June 1907 is to look at the town mark, the symbol that shows which assay office carried out the assay and hallmarking.
After 1 June 1907 all gold and silver watches imported into Britain were required to be assayed and hallmarked in a British assay office.