The short answer
131.23 is not a model name and it is not a serial number. It is the middle of an Omega product code, and on the current Constellation line that block describes a two-tone watch: stainless steel paired with gold. So when someone searches for a fake Constellation 131.23, they are usually staring at a listing that copied a real reference string onto a counterfeit. The photo can look convincing. The paperwork behind it never does. Three things separate the two quickly: the METAS certificate lookup, the reference number itself, and the finish on the case claws.
How to read the reference
A full Omega code looks like 131.23.41.21.01.001, and every block carries information. Print it out mentally and the whole thing becomes a specification sheet.
- First block (131): collection and case metal family, here the modern Constellation.
- Second block (23): bracelet style and metal mix. This is where two-tone lives.
- Third block (41): case diameter in millimetres.
- Fourth block (21): movement family.
- Fifth block (01): dial colour and finish.
- Last block (001): the exact variant.
That structure is useful. If a listing shows a dial colour that does not line up with the fifth block, walk away. Replica sellers reuse one code across four or five dials because most buyers never read the last three digits. Check the whole string against the brand's own product page, not against the seller's description.
Why counterfeits cluster on this reference
Two-tone Constellations photograph beautifully. The claws, the Roman numeral bezel and the mono-rang bracelet all read as expensive on a phone screen, and the reference is long enough to feel official. That combination is the whole business model for a certain tier of replica. It also means the fakes are common enough that a real one needs checking, not assuming.
The checks that actually work
METAS and the Master Chronometer card
Modern 39mm and 41mm Constellations run Master Chronometer movements in the 8800 and 8900 families. Each one is tested by METAS and ships with a card carrying an eight-digit test number, and that number is searchable in the public database. A replica cannot produce a matching entry. Sellers either show no card or show a number that returns nothing. Ask for a photo of the card and the caseback in the same frame.
Case claws
The griffes at 3 and 9 are the giveaway. On a real watch they are cut from the case itself, polished on the flat and satin on the flank, with a crisp break between the two surfaces. Cheap fakes mill them soft or glue them on, and the transition looks rounded under magnification. Drag a fingernail across the edge. It should catch, not slide.
Bezel
The Roman numerals are engraved into the bezel and filled, never printed on top. Spacing is even, and the half-moon facets between numerals are polished to a mirror. On fakes the numerals run thick, the fill sits proud of the surface, or the facets look dull.
Movement
Through a sapphire caseback you want a free-sprung balance, a silicon hairspring, arabesque Cotes de Geneve striping, blackened screws and a rotor engraved with the co-axial text. Replicas show a decorated generic automatic, typically with a regulator arm on the balance cock and a plainly metallic hairspring.
Gold that lasts or wears
This failure shows up over months rather than on day one. Inspect the clasp edges, the crown and the underside of the bracelet where it rubs the wrist. Plated gold thins and greys there. Solid gold does not.
Paperwork
Omega ships pictogram cards and a Master Chronometer card. Numbers on the cards, the caseback and the movement should correspond. Some replica sets even match those numbers to each other, which sounds reassuring until you run them through METAS.
Price is the loudest tell
A two-tone Constellation 41mm sells new in the high four figures to five figures in USD. Used examples rarely fall below a few thousand. A listing at a few hundred dollars is a counterfeit, whatever the photos show and whatever story comes with it.
If you buy the replica anyway
Go in clear eyed. Plating wears at the clasp and crown. The movement is a Chinese automatic with no parts network, so a service can cost more than the watch. Water resistance is a guess. Resale is effectively zero. And importing counterfeit goods into the United States is illegal, which means CBP can seize the shipment and the buyer can face civil penalties. Paying by card leaves a trail. That is the trade.
Quick checklist before you pay
- Paste the full reference into a search and confirm the watch exists.
- Request the METAS number and look it up yourself.
- Get daylight photos of the claws, bezel and clasp edges.
- Match the dial colour to the fifth block of the code.
- Compare the asking price against the current market.
- If any of that is refused, walk away.