On a replica listing, "291" is almost never an Omega reference. It is a batch or version code a seller or factory uses for one production run of Seamaster 300M replicas, usually the 42mm diver. Two listings can carry the same number and ship different watches, because the code tracks production, not specification. Use it as a starting point, then verify the case, dial, bezel, and movement yourself before you pay.
Genuine references versus seller codes
Real Seamaster references are long numeric strings such as 210.30.42.20.01.001, where each block stands for a family, case size, material, and dial variant. "291" fits none of that pattern. When I see a short code, I look for the case size, dial color, bracelet style, and movement listed separately. If a seller cannot name the factory and the movement inside, the number is decoration.
What makes the 300M recognizable
- 42mm case, roughly 13.5mm thick, about 50mm from lug to lug
- Ceramic bezel insert with a white enamel or gold diving scale
- Laser-engraved wave dial on the current generation
- Helium escape valve at 10 o'clock
- Conical crown guards and a signed screw-down crown
- Date at 6, no magnifier over it on any version
That last point trips up a lot of buyers. The Seamaster 300M has never used a cyclops, so a replica with one is wrong out of the box.
Movement is the deciding factor
Most sub-$300 replicas run a basic A2824 or a Miyota 8215. They keep time, they are cheap to service, and the beat rate is usually 28,800 vph. Better batches use a decorated clone that mimics the finish and rotor engraving of the Co-Axial Calibre 8800. It looks closer through an exhibition caseback, and it costs more. Neither is a Master Chronometer, and neither has been magnetically tested the way the genuine article has. If a seller claims METAS certification on a replica, that is a straight fabrication.
Bezel, crown, and the small stuff
Bezel action separates good batches from bad ones. A genuine 300M clicks cleanly through 120 positions with no backplay. Cheap replicas feel gritty or spin loosely. Check the enamel fill for overflow, and look at whether the triangle aligns with 12 o'clock when the bezel is centered. The crown should thread smoothly in several turns and sit flush against the guards. The helium valve on a replica is cosmetic in nearly every case, and it usually is not sealed.
Sizing and daily wear
The bracelet runs 20mm at the lugs and tapers toward 18mm at the clasp. On a 6.5 inch wrist the 42mm case wears large but not absurd, mostly because the lugs curve down. If your wrist is under 6.5 inches, the 42mm may overhang. Nobody makes a perfect 36mm alternative, so plan on the bracelet fit being the deciding comfort factor.
Quick inspection checklist
- Ask which factory and which movement. Vague answers are a red flag.
- Request photos of the bezel edge and the crown threads, not just the dial.
- Confirm no cyclops over the date.
- Compare lume color between hands and markers under a lamp.
- Check the bracelet end links for gaps against the case.
- Assume the water resistance is decorative. Do not swim with it.
Honest limits
A replica Seamaster is not a Seamaster. It has no warranty, Omega will not service it, resale value is close to zero, and a trained eye will spot it across a table. Buy it as a look, not as an asset. If what you want is the actual watch, save for the real one and the 291 code stops mattering entirely.