HOW WE VERIFY MARKS
Every entry in this library describes a physical marking — what it usually means, where it appears, and how it varies. This page explains where that information comes from and how it is checked before it is published.
Where our information comes from
Entries are compiled from primary and authoritative sources wherever they exist: national hallmarking legislation (such as the UK Hallmarking Act 1973), assay office publications, international standards (ISO 22810 and ISO 6425 for water resistance, millesimal fineness conventions for precious metals), trade regulations (the FTC jewelry guides in the United States), and manufacturer documentation and archives for brand-specific serial and reference systems.
Where a page rests on a specific standard or archive, it lists that reference in a Sources section at the end of the page.
How entries are reviewed
Each entry is drafted against the sources above, then reviewed for accuracy and consistency before publication. Pages carry a visible reviewed date; when an entry is materially updated — new variants, a corrected attribution, added reference data — the date is updated with it. We do not change dates without changing content.
What we will not claim
Markings can be forged, altered, worn, or inconsistent across production runs. For that reason this library deliberately avoids claims of certainty: we describe what a mark usually indicates, not what it proves. No page on this site — and no result from our AI check tool — is an authentication, appraisal, or valuation. For decisions that matter, we consistently recommend a qualified watchmaker, jeweler, or assay office.
Corrections
If you spot an error, we want to know. Contact us via the details on our About page and include the page URL and the source for the correction. Verified corrections are applied to the entry and reflected in its reviewed date.