Watch School

  1. Guide to Owning a Mechanical Watch
  2. Watch Reference Numbers

How to Understand Watch Reference Numbers

Have you ever been on a watch forum or chatting with a collector and they mention a reference number? At first glance, it’s some seemingly random, long string of digits that indicates something about the watch. But what?

Table of Contents

In general, a reference number is simply an easy, shorthand way to identify the watch. Most numbered reference systems are broken into digits, with each one telling us something about the timepiece. The first digit, on an Omega watch, for example designates the model. The 2nd digit represents the material type and combination of the case and bracelet.

It should be noted that reference numbers are not serial numbers, which may be used to indicate authenticity and date when a watch was created.

Below we’ve included a quick look at 2 major watch manufacturer reference number systems.


Modern Omega watches have a numbering system called PIC (product identification code). An example is the popular Omega 3750. (Editors note: argh, Omega just recently changed to an entirely new reference system: the 3750 became the 311. Here is a table by ChronoMaddox below:



A popular example of a Rolex model that often includes a reference number is the Steel Daytona, ref 16520. Rolex uses a very straightforward system, quite similar to Omega, above. They range from 4-6 numbers and recently (around 2000 or so) may have an additional 1 at the beginning. You can find the digits between the lugs at the 12 o’clock position.


Now that we’ve taken a quick look at the various systems used by manufacturers, hopefully this clears it up for you. It’s really not all that complex, and it’s highly useful when you know what you’re looking for. Instead of telling someone you’re looking for a “Omega Speedmaster, steel gold case on leather strap, with the champagne dial color”… you can just say ‘Speedmaster ref 3750’!