Short answer
Replica Constellation Master Chronometer 151 is a copy of the Omega Constellation Master Chronometer. Omega does not use 151 as a model number for this line. Sellers use 151 as a catalog or batch code. The real watch runs Omega calibre 8900, a movement certified by METAS as a Master Chronometer and rated against a magnetic field of 15,000 gauss.
What the genuine watch is
The Constellation Master Chronometer entered the Omega line in 2015. The main case size is 39mm in stainless steel. Omega also sells 36mm and 41mm versions. The design keeps the two claws at 3 and 9 o'clock that have been on the Constellation since 1982. The bezel carries half moon facets. The dial has a date window at 6 o'clock.
Core specs
- Case: 39mm stainless steel, 50m water resistance.
- Movement: Omega calibre 8900, automatic, two barrels in series, 60 hour power reserve.
- Escapement: co-axial, with a silicon balance spring.
- Certification: METAS Master Chronometer, eight tests over 10 days.
- Magnetism: 15,000 gauss.
- Crystal: domed sapphire front, sapphire back with the Observatory medallion.
What 151 means
Omega catalogs list the 39mm Constellation Master Chronometer under reference numbers that start with 131. A real reference reads like 131.10.39.20.01.001. The digits 151 do not fit that pattern. Treat 151 as a code from the seller, not from Omega. Two sellers can use 151 for two different builds. Ask for the exact case size before you pay.
What to check on a copy
- Movement. Most copies use a decorated automatic movement from Asia. It is not a co-axial 8900. Look at the rotor engraving and the beat rate. Ask the seller for the movement name.
- Case size. Ask for the diameter in millimeters. A 41mm copy is not the 39mm watch.
- Dial print. The words MASTER CHRONOMETER sit under the Omega logo. Check the letter spacing and the date font.
- Bracelet and clasp. The half moon links should move without rattle. Check the clasp engraving.
- Caseback. A sapphire back shows the movement. A solid back hides it.
The certification gap
No copy passes the METAS Master Chronometer tests. The eight tests cover rate, power reserve, and magnetic exposure. A 15,000 gauss rating comes from a silicon balance spring and non magnetic parts. A copy with a steel balance spring will drift near a magnet. Ask the seller what accuracy to expect. Figures for copies run from about -20 to +30 seconds a day. The real watch is certified to 0 to +5 seconds a day.
Price band
Listings for this copy fall between $150 and $600. Movement type drives the price. Shipping terms and warranty length vary by seller. Get the return window in writing before you order.