An Omega reference looks like a phone number: 310.30.42.50.01.002. It is long, but it is not random. Each group of digits describes one thing about the watch, and once you know the order you can tell two similar Omegas apart without opening a photo.
That matters when you buy. Two Speedmasters can look the same in a small picture and differ in crystal, strap and price. The reference settles it. This guide explains the system Omega has used since 2007, with examples you can check against the 2,491 Omega watches we have in stock.
Reference number, serial number and caliber
Three numbers come with every Omega, and they do different jobs:
- The reference number identifies the model: every watch built to the same specification shares it. Omega calls it the PIC, for Product Identification Code.
- The serial number identifies one individual watch. On a modern Omega it has eight digits and is engraved on the case, usually on the back of a lug or on the case back.
- The caliber number, such as 3861 or 8800, identifies the movement inside.
The reference and the serial number are both printed on the warranty card. When you compare prices, compare watches with the same reference. When you check that a watch and its papers belong together, compare the serial numbers.
The structure: six groups, fourteen digits
A modern Omega reference has fourteen digits in six groups:
| Group | Digits | What it tells you |
|---|---|---|
| 1 | 310 | Collection |
| 2 | 30 | Case material and bracelet or strap |
| 3 | 42 | Case diameter in millimeters |
| 4 | 50 | Type of movement and complications |
| 5 | 01 | Dial color |
| 6 | 002 | Sequence number |
Read from left to right, the reference goes from the general to the specific: which family, what it is made of, how big it is, what drives it, and what the dial looks like.
Group 1: the collection
The first digit names the family:
| First digit | Collection |
|---|---|
| 1 | Constellation |
| 2 | Seamaster |
| 3 | Speedmaster |
| 4 | De Ville |
| 5 | Special and limited releases |
The next two digits narrow it down to a line within the family. Among the watches we stock most, 310 is the Speedmaster Moonwatch Professional and 210 is the Seamaster Diver 300M. So a reference that starts with 2 is always a Seamaster, and one that starts with 3 is always a Speedmaster, whatever the seller's title says.
Group 2: case material and bracelet
The second group has two digits. The first describes the case material in broad terms:
- 1, 2 or 3: the case is mainly steel
- 5 or 6: the case is mainly gold
- 9: another material, such as titanium or ceramic
The second digit describes what the watch is worn on. The easiest way to learn it is to compare two references that differ only here. In the Speedmaster Moonwatch and the Seamaster Diver 300M, 30 is a steel watch on a steel bracelet and 32 is the same steel watch on a strap:
- 310.30.42.50.01.002: Moonwatch on the steel bracelet
- 310.32.42.50.01.002: the same watch on a strap
- 210.30.42.20.01.001: Seamaster Diver 300M, black dial, steel bracelet
- 210.32.42.20.01.001: the same watch on the rubber strap
This is the group to read first when a price looks low: the strap version of a watch usually costs less than the bracelet version, and the bracelet is expensive to add later.
Group 3: the case size
The third group is the case diameter, rounded to two digits. In 310.30.42.50.01.002 it is 42, for the 42 mm Moonwatch. An Aqua Terra reference with 41 here is the 41 mm watch, and one with 38 is the 38 mm.
Omega makes many models in several sizes with the same name, so this group saves mistakes. If you are choosing between sizes, our guide to choosing your watch size explains how the numbers translate to the wrist.
Group 4: the movement
The fourth group describes the movement. Its first digit gives the type:
| First digit | Movement |
|---|---|
| 0 | Mechanical |
| 1 | Mechanical, chronometer certified |
| 2 | Mechanical with Co-Axial escapement |
| 3 | Mechanical chronograph |
| 4 | Mechanical chronograph, chronometer certified |
| 5 | Mechanical chronograph with Co-Axial escapement |
| 6 | Quartz |
| 7 | Quartz chronograph |
The second digit marks complications added to the basic movement. A Seamaster Diver 300M has 20: a Co-Axial automatic with nothing added beyond the date it is built with. The Moonwatch has 50: a Co-Axial chronograph.
This group is the quick way to separate quartz from mechanical in the Constellation and De Ville families, where the two are sold side by side and look alike. A 6 at the start of the fourth group means quartz.
Group 5: the dial
The fifth group is the dial color. The codes you will meet most often:
| Code | Dial |
|---|---|
| 01 | Black |
| 02 | Silver |
| 03 | Blue |
| 04 | White |
| 06 | Gray |
| 10 | Green |
So the Seamaster Diver 300M in steel on a bracelet is 210.30.42.20.01.001 with a black dial, 210.30.42.20.03.001 in blue, 210.30.42.20.04.001 in white and 210.30.42.20.10.001 in green. Four watches, one digit pair apart.
Higher codes cover special dials, such as those set with stones or made of unusual materials. For those, rely on the listing and the photographs.
Group 6: the sequence number
The last three digits separate watches that share everything in the first five groups. They are given out in order, so they have no fixed meaning, but they can make a real difference.
The best-known case is the Moonwatch. 310.30.42.50.01.001 and 310.30.42.50.01.002 are both steel Moonwatches on a bracelet with a black dial and the caliber 3861. The difference is the crystal and the case back:
- .001 has the Hesalite crystal, the acrylic glass of the watches worn on the Moon, and a closed steel case back.
- .002 has a sapphire crystal on the front and a sapphire case back that shows the movement.
They are priced differently, and buyers usually want one or the other. We have 11 of the sapphire version in stock, from $4,970, and 9 of the Hesalite version, from $4,620. Our Speedmaster buying guide explains how to choose between them.
Three references, read in full
310.30.42.50.01.002 Speedmaster Moonwatch (310), steel on a steel bracelet (30), 42 mm (42), Co-Axial chronograph (50), black dial (01), sapphire version (002).
210.32.42.20.03.001 Seamaster Diver 300M (210), steel on a rubber strap (32), 42 mm (42), Co-Axial automatic (20), blue dial (03), first version (001).
210.90.42.20.01.001 Seamaster Diver 300M (210), a case in a material other than steel or gold (90), 42 mm (42), Co-Axial automatic (20), black dial (01). This is the titanium Diver 300M on a titanium mesh bracelet. The second group told you it was not a steel watch before you read anything else.
Older Omega references
Before 2007, Omega used a shorter reference of eight digits, written as four, two and two: 3570.50.00 is the Speedmaster Professional of that period, and 2254.50.00 is a well-known Seamaster 300M. You will see this format on pre-owned watches made before the change, and for some years the two systems overlapped.
The old numbers follow their own logic and are best looked up one at a time. If you are considering an older Omega, send us the reference on WhatsApp and we will tell you exactly what it is.
How to use the reference when you buy
- Find it on the listing. Every Omega on our site shows its reference under the title and in the specifications.
- Read groups 2 and 3 first. Material, bracelet and size explain most price differences between watches with the same name.
- Check group 4 on dress models. It tells you whether a Constellation or De Ville is quartz or mechanical.
- Compare the last three digits. Where two versions exist, as with the Moonwatch, they are different watches.
- Match it to the papers. The reference on the warranty card should be the one on the listing, and the serial number on the card should match the watch.
Search engines and our own search box both understand references. Type the full number, with or without the dots, and you will find the exact watch. Our guides to box and papers and to buying a luxury watch online safely cover the rest of the checks.
Related guides: Omega Constellation buying guide · Omega De Ville buying guide · Omega Seamaster buying guide
Frequently asked questions
Where is the reference number on an Omega?
On the warranty card and on the hang tag that comes with the watch, and on the listing. The number you will always find on the watch itself is the serial number, so read the reference from the papers.
Where is the serial number on an Omega?
On a modern Omega it is an eight-digit number engraved on the case, usually on the back of one of the lugs or on the case back, and it is repeated on the warranty card.
What do the last three digits of an Omega reference mean?
They are a sequence number that separates watches sharing the same collection, material, size, movement and dial color. On the Speedmaster Moonwatch, for example, .001 is the Hesalite version and .002 the sapphire version.
How can I tell from the reference if an Omega is quartz?
Look at the fourth group of digits. If it begins with 6, the watch is quartz; if it begins with 7, it is a quartz chronograph. The groups beginning with 0 to 5 are mechanical.
Does the same reference always mean the same watch?
Yes, as it left the factory. A pre-owned watch may have had its strap or bracelet changed since, so check the photographs and the description as well as the number.
Is Watchflix NYC an official Omega retailer?
No. We are an independent retailer and are not affiliated with Omega. Every watch is checked by our specialist before it ships.
