What does “Serial” mean?

The serial number is the unique number of an individual watch, assigned by the brand. Two watches of the same reference share a reference number but never a serial. On modern Rolex watches the serial is engraved on the rehaut, the inner ring between the dial and the crystal; older models had it on the case between the lugs at 6 o'clock. Other brands often engrave it on the case back or the case.

The serial links a watch to its papers, service records and, for some brands, archive records, and it is used to date older pieces. A matching serial on watch, card and tags is a basic authenticity check. Because a serial can identify a specific watch and its owner, dealers often share it only with serious buyers. Stolen-watch registers also work by serial, and checking a serial against one before buying is sensible, especially for valuable pieces.

Example: 'Serial available to serious buyers; card and watch match.'