ABOUT WHATISTHISMARK
WhatIsThisMark is an independent reference library for identifying markings on watches and jewelry — from case-back codes and serial numbers to hallmark stamps, purity marks, and maker signatures.
Whether you inherited a family watch, found a ring at an estate sale, bought a piece at a flea market, or simply want to know what the numbers stamped inside your jewelry mean — this site is your starting point.
Our Approach
We research, compile, and present identification information in a clear, educational format. Our library currently covers 13 major watch brands, 34+ watch markings, 25+ jewelry hallmark guides, 10 jewelry maker profiles, and in-depth topics spanning water resistance ratings, gold karat systems, silver purity stamps, and British hallmarking.
We also offer an AI-powered mark checker that analyzes photos of watches and jewelry to generate structured observations about visible markings. This tool is for educational guidance only — not professional authentication or appraisal.
Editorial Independence
WhatIsThisMark is not affiliated with, endorsed by, or sponsored by any watch manufacturer, jewelry brand, dealer, or marketplace. Our guides are written to be accurate and helpful, not to promote any product or service.
Important Limitations
Markings on watches and jewelry can be reproduced, altered, or vary between production runs. Hallmarks can wear down or be counterfeited. No online resource — including AI analysis — can definitively authenticate a piece from photos alone. For authentication or valuation, always consult a qualified watchmaker, jeweler, or authorized dealer.
Who Maintains This Site
WhatIsThisMark is maintained by an independent collector and enthusiast. Content is researched using manufacturer documentation, assay office records, published collector references, and community-verified data. We are not professional watchmakers, jewelers, or appraisers — this site is a research starting point, not a final authority.
Our Editorial Process
Every guide on WhatIsThisMark follows a consistent editorial process designed to ensure accuracy and usefulness:
- Primary research — We reference official manufacturer documentation, service manuals, and published technical specifications wherever available.
- Community verification — Information is cross-referenced against established collector communities, forums, and published reference books.
- Regular updates — Content is reviewed and updated periodically. Each page displays its publication and last-modified dates so you can assess freshness.
- Transparent limitations — We clearly state what our guides can and cannot tell you. We never claim to offer authentication — only educational guidance.
Content Coverage
As of 2026, WhatIsThisMark covers:
- 13 major watch brand identification guides
- 34+ common watch marking explainers
- 25+ jewelry hallmark guides including international systems
- 10 jewelry maker identification profiles
- In-depth topic guides on water resistance, movement markings, gold karats, silver purity, British hallmarks, and more
- An AI-powered photo analysis tool for preliminary identification
- An interactive mark lookup wizard for quick identification
Contact
Questions, corrections, or feedback: hello@iron-pig.com
If you spot an error in any of our guides, please let us know. Accuracy is our top priority, and we appreciate corrections from knowledgeable collectors and professionals.