Short answer

Omega Constellation 131 is the current generation of the Constellation line. The 131 prefix is Omega's product code for this family. Replica versions copy the case, dial, bezel and bracelet. They do not copy the co-axial movement, the escapement, or the METAS Master Chronometer certificate. A replica 131 runs on a third-party automatic or a decorated clone. Case size on replicas often lands 0.3 mm to 0.8 mm off the genuine number.

How to read a 131 reference

Omega reference numbers use six groups split by dots. A full number looks like 131.10.39.20.01.001.

  • Group 1, 131: Constellation, current generation.
  • Group 2, 10: stainless steel case and bracelet. Steel and gold versions use other codes in this slot.
  • Group 3, 39 or 41: case diameter in millimeters.
  • Groups 4 and 5: dial and movement codes.
  • Group 6, 001: bracelet or strap variant.

Omega does not publish a full decoder. The digits above match numbers printed in the Omega catalog and in dealer listings.

Genuine specs for the 131 line

  • Case: 39 mm or 41 mm. Stainless steel, or steel with Sedna or yellow gold.
  • Thickness: about 12.5 mm on the 39 mm steel model.
  • Crystal: domed sapphire with anti-reflective coating on two faces.
  • Bezel: polished, with Roman numerals. Two claws sit at 3 and 9 o'clock.
  • Bracelet: mono-bracelet with a butterfly clasp. No end links.
  • Movement: caliber 8800 on 39 mm, caliber 8900 on 41 mm. Both carry Master Chronometer certification.
  • Water resistance: 50 m.
  • Magnetic resistance: 15,000 gauss.
  • Power reserve: 55 hours on caliber 8800, 60 hours on caliber 8900.
  • Date window: 6 o'clock.

What changes on a replica

  • Movement: a Seagull or Hangzhou automatic, or a decorated clone of the 8800. The rotor carries Omega engraving.
  • Crystal: sapphire on top tiers, mineral glass on cheap builds.
  • Bezel numerals: printed or laser-etched on replicas. Genuine uses ceramic with Ceragold or Liquidmetal inlays on several references.
  • Bracelet: solid links on mid tiers, folded links on low tiers. Clasp stamping is shallow.
  • Case back: engraved serial and reference. Engraving depth is the first tell.
  • Balance: replica 8800 clones use a conventional balance. Genuine caliber 8800 uses a free-sprung balance with a silicon spring.

Checks before you buy

  1. Measure the case with calipers. A 39 mm build should read 39.0 mm to 39.3 mm across the case, not the bezel.
  2. Look at the claws. Both sit flat against the case flank, with an even gap.
  3. Read the dial print. CONSTELLATION sits below 12, CO-AXIAL MASTER CHRONOMETER above 6.
  4. Check the date aperture at 6. Font weight and window cut vary by factory.
  5. Check bracelet end fit. A gap above 0.2 mm at the lugs shows on the wrist.

Price bands

Replica Constellation 131 prices run from about $120 for a mineral-glass build to $450 and up for a clone movement and sapphire crystal. Genuine 131 references list from about $6,000 in steel to more than $20,000 in solid gold. No replica holds resale value. In the United States, selling a counterfeit watch carries criminal penalties under 18 U.S.C. 2320.