Quick answer: A fake Constellation 131.20 gives itself away at the case, where the claws and polished bevels look soft or over-polished, and at the dial, where the star, the OMEGA wordmark, or the date window sits off-center or uses the wrong font weight. A genuine 131.20 carries a Master Chronometer movement behind a sapphire caseback, a signed crown, and end links that meet the lugs with no gap.
What Ref. 131.20 Covers
131.20 is the material and case code Omega uses for current-generation Constellation models in steel and gold. The digits that follow identify size, dial, and bracelet. That matters for authentication because each full reference has published specs: case diameter, lug width, water resistance, and movement. A seller who cannot match the full reference to the factory spec page is offering something the factory never built.
The Checks That Matter Most
Case and claws
Genuine Constellation cases have four polished claws that grip the bezel. On replicas the claws run thick, spill past the bezel edge, or sit at uneven depths. Run a fingernail across the join. A genuine case feels flush; a replica catches.
Dial, star and date window
The applied star should sit centered above the wordmark with even spacing. Replica dials show the star tilted, the print heavy, or the date window cut rough. On genuine 131.20 dials the date disc sits level with the dial surface and the numerals stay crisp under magnification.
Caseback and movement
Current Constellation models use a sapphire caseback with an engraved case number that matches the warranty card and the movement. Clone movements show a plain rotor, missing Co-Axial text, or a balance wheel in the wrong position. If the caseback is solid on a reference that should be open, walk away.
Bracelet and clasp
Genuine bracelets have sharp, even link edges, tight end-link fit, and a clasp with deep engraving. Replicas show rounded link corners, gaps at the lugs, and shallow laser etching that rubs off with wear. Weigh the watch. A genuine 131.20 in steel and gold lands near the published weight; a clone runs light.
Step-by-Step Authentication Check
- Read the full reference off the caseback and compare it to the factory spec listing for that exact number.
- Check the crown for the Omega symbol and confirm it screws down with no wobble.
- Inspect the claws at 10, 2, 4, and 8 o'clock for even thickness and a flush join with the bezel.
- Study the dial under 10x magnification for print edges, star alignment, and date window finish.
- Turn the watch over and confirm the sapphire caseback, engraving depth, and movement layout.
- Match the case number on the back to the number on the warranty card and the movement bridge.
- Check the bracelet end links for gaps and the clasp for crisp, deep engraving.
- Weigh the watch against the published spec and test the rate on a timegrapher.
Where Super Clones Still Fall Short
The best replicas copy the outside well. The gap shows in the movement, in the finishing of parts you cannot see at arm's length, and in paperwork. If you buy a replica, buy it as a replica and know the tells. If you buy a genuine 131.20 secondhand, ask for service records, run the steps above, and have a watchmaker open the case before money changes hands.