Horology glossaryDefined term / hallmark
Hallmark
An official stamp applied by an assay office certifying the purity of a precious metal case, required in some countries for gold and platinum items.
Authentication note
Why this detail matters.
Hallmarks indicate the metal content and, depending on the country, the assay office and year of testing, which can help corroborate a case's material claims and sometimes its period. A missing hallmark where local law requires one, or a hallmark inconsistent with the case's claimed metal, is worth flagging.