Short answer
Omega caliber 1511 is a thermocompensated quartz movement. Omega built it for the Marine Chronometer line in the 1970s. The caliber 1510 came first. The 1511 followed as a revised version. Both are quartz, not mechanical. A replica Omega 1511 is a case and dial made to look like those watches. The module inside a replica is not a 1511.
What the 1511 is
Omega introduced the Marine Chronometer in 1974. The watch used a quartz oscillator plus a compensation circuit that offset temperature drift. Omega quoted a rate of 5 seconds per year for the Marine Chronometer. Standard quartz watches of that era ran at about 5 seconds per month or worse.
The 1510 and 1511 differ in small details of circuit and layout. Service documents list both as high-accuracy quartz calibers. Production totals are not public. Jewel counts reported by collectors do not all agree, so treat any single figure with caution.
Omega stopped making the movement decades ago. Parts supply is thin.
What a replica can and cannot copy
- Copyable: case shape, bezel, crystal profile, dial print, hand type, crown, caseback text.
- Not copyable at replica prices: a thermocompensated quartz module with a 1511 rate.
- Inside a replica: a generic quartz module from a third-party factory. Rate is about 15 to 20 seconds per month.
- Date change, stem length, and battery type on a replica will not match Omega service data.
Points to compare against a real reference
- Case diameter and thickness, measured with calipers.
- Dial print weight and font. Originals use thin, even lettering.
- Caseback engraving depth and reference number format.
- Serial numbers. Cross-check the range for the reference.
- Bracelet end links and clasp stamping.
- Crystal material and edge profile.
Reference numbers matter more than the caliber name. A seller who lists 1511 without a case reference has given you nothing to verify.
Legal and service facts
Counterfeit watch sales are illegal in the United States. 18 U.S.C. 2320 covers trafficking in counterfeit goods. Omega does not service counterfeit watches and does not authenticate them.
Servicing a genuine 1511 is its own problem. Parts are scarce. Some service centers replace the module instead of repairing it, which lowers originality.
Price gap
Genuine Marine Chronometers sell in the thousands of dollars at auction and on watch marketplaces. Replica versions sell for tens of dollars to a few hundred. The difference is the movement, not the case finish.