Short answer
The "fake Constellation Master Chronometer 151" is a replica of the Omega Constellation Master Chronometer 39 mm. "151" is not an Omega reference prefix. Omega reference numbers for the Constellation Master Chronometer line start with 131. The 151 tag comes from sellers, not from Omega. The origin of that number is not documented.
What the genuine watch is
Omega sells the Constellation Master Chronometer in 39 mm and 41 mm cases, in steel, steel with gold, and solid gold. The 39 mm steel model runs caliber 8800. That movement uses a Co-Axial escapement, a silicon balance spring, and a free-sprung balance. METAS certifies each watch as a whole, not the movement alone.
Master Chronometer certification covers 8 tests over 10 days. The limits are 0 to +5 seconds per day, rate in 6 positions, rate at low power reserve, and function after exposure to a 15,000 gauss magnetic field. Each certified watch ships with an 8-digit code tied to its test record.
Price tiers in the replica market
Listings cluster in three groups. Entry fakes run USD 80 to 200 and often use quartz or a low-grade automatic. Mid-tier fakes run USD 250 to 500 and copy an ETA 2824 or a Miyota layout. Top-tier fakes run USD 500 to 900 and use the term super clone. No replica carries a METAS-tested movement. METAS tests watches one at a time and logs the result, so a copied code fails a lookup.
Checks that separate the two
- Certificate: the 8-digit Master Chronometer code on the card and in the METAS database.
- Movement: caliber 8800 has a silicon balance spring, a free-sprung balance, and arabesque finishing on the rotor. Replicas show ETA or Seiko-style bridges, different rotor screws, and a regulator index.
- Case: 39 mm across, claws at 3 and 9 o'clock, integrated bracelet, butterfly clasp.
- Dial: applied star, printed "Constellation", and a date window aligned with the crown.
- Price: a new steel Constellation 39 mm from an authorized dealer costs about USD 6,000. Offers far below that are not genuine stock.
Legal status in the United States
19 U.S.C. 1526(e) bans import of goods bearing a counterfeit mark. U.S. Customs and Border Protection can seize a shipment and destroy it. The buyer absorbs the loss. Selling a replica as a genuine watch is trademark infringement and can carry civil damages.
Service and parts
Omega service centers do not take replicas. Parts such as the silicon balance spring, the crown, and the sapphire crystal come from Omega. A replica with a failed movement gets a generic swap or no repair at all. Resale value on a replica is near zero.
What is not known
No source ties "151" to a specific factory, batch, or case number. Treat the number as marketing text on a listing and check the watch, the code, and the price instead.