Reference Library
Resources
These are the references I lean on when authenticating and dating the watches that come through Crowned Koi. None of this is a substitute for a physical inspection — a clean serial doesn't prove a watch is original, and a missing one doesn't prove it isn't — but every one of these data points is part of the story a watch tells.
Pick a topic below. If you have a piece you're trying to verify or date and want a second set of eyes, email pat@crownedkoi.com with photos.
Rolex Serial Numbers
Year-by-year production chart from 1926 to today, plus where to find the serial on case and rehaut.
Rolex Clasp Codes
Letter-and-number stamp on the inside of the clasp — when paired with a serial, it tells you the bracelet's year.
Rolex Country Codes
The 3-digit code on warranty papers that identifies which authorized dealer first received the watch.
Red Letters on Warranty Papers
The red shipping stamp on US-paper certificates, decoded — Rolex USA's audit trail from headquarters to dealer.
Rolex and Tudor
How the two brands are related, what they share, and how to think about Tudor as a collector.