Where to Find Your Watch's Reference and Serial Number

When someone emails about "my father's gold Rolex", there is nothing to value. There are dozens of gold Rolex references across six decades, and the gap between the least and most sought-after is enormous. One number closes that gap instantly.

Here is where to look, by maker, plus what each number actually tells someone.

The difference between the two numbers

The reference number describes the model and its configuration: case material, bezel type, dial layout, bracelet. Every watch built to that specification shares it. It is the number that tells a buyer what your watch is.

The serial number is unique to your watch. It dates the piece, and it is what gets checked against paperwork and against theft databases. It is the number that tells a buyer which watch it is.

A valuation needs the reference. A transaction needs both.

Rolex

On a modern Rolex the reference is engraved between the lugs at 12 o'clock, hidden under the bracelet. Seeing it means removing the bracelet or a spring bar, which most owners should not attempt. The easier route: the reference is also printed on the warranty card, and the first four or five digits are usually enough to identify the model.

The serial moved over the years. On watches from roughly 2005 onward it is laser-engraved on the rehaut, the sloped inner ring between the dial and the crystal, at the 6 o'clock position. It is fine, and it catches the light at an angle rather than head on. Tilt the watch under a lamp and it will appear.

On earlier watches the serial is engraved between the lugs at 6 o'clock, again under the bracelet. Vintage pieces from the 1980s and before use shorter serials without the modern letter prefix.

Patek Philippe

Patek engraves the reference on the caseback, usually alongside the case material hallmark. There are two serials to know about: the case number on the caseback, and the movement number inside, which is the one Patek's archive uses.

You do not need to open the watch. The case number is enough to start, and an Extract from the Archives, which Patek issues on request to the owner, confirms the movement number, the date of manufacture and the original configuration. If you have an Extract, it is one of the most useful documents you can hand a buyer.

Audemars Piguet

Both numbers are generally on the caseback. The reference typically appears as a longer alphanumeric string encoding the case material and dial, and the serial is a shorter number, often preceded by a letter. On Royal Oak models the engraving can be fine and set against a brushed surface, so angle the light rather than increasing it.

Omega

Omega's reference, which the brand calls the PIC or product identity code, is on the caseback on modern watches and runs to eight digits with periods. The serial is a six to eight digit number found on the caseback, or occasionally on a lug on older pieces. Vintage Omegas often carry the serial on the movement, which does require opening the watch, so if the caseback shows nothing, work from the reference and the photographs instead.

Cartier

Cartier typically engraves the reference and serial on the caseback, and on many models the serial also appears on a lug or on the case side. Santos and Tank models vary by generation, so check the caseback first and the lugs second.

If you find nothing

It happens, and it is not a problem. Casebacks get polished, engravings wear, and some vintage cases never carried an outside serial at all. In that situation the identification comes from the watch itself: dial text, handset, bezel, case shape, bracelet and clasp codes together narrow a watch down reliably.

This is exactly what good photographs are for. A clear shot of the dial, the caseback and the clasp will usually let a specialist identify a reference with no engraving at all.

What to do with the numbers once you have them

• Write them down somewhere other than the watch. If it is ever lost or stolen, the serial is the single most useful thing you can give the police and your insurer. It should be in your records whether or not you are selling.
• Photograph them. A legible photo of the rehaut or caseback saves repeating the number down a phone line and getting a digit wrong.
• Check them against your paperwork. The serial on the watch should match the serial on the warranty card. If it does not, find out why before starting a sale, because a buyer will certainly notice.

With the reference in hand, the first conversation about your watch is about your watch. That is worth two minutes under a lamp.

Common questions