Short answer
A fake Seamaster 300M 291 is a replica of Omega's 42 mm Seamaster Diver 300M sold under the 291 listing code that many first copy sellers use for the ceramic dial, wave pattern version. The 291 is not an Omega reference number. It is a seller code, and it covers a wide range of quality. A basic quartz copy and a Super Clone with a decorated automatic movement can both sit under the same 291 label, so the code alone tells you nothing about build quality. You have to inspect the case, bezel, dial, movement and bracelet as separate items.
What buyers get wrong about the 291
Most buyers treat 291 as a specification. Sellers encourage this because it lets one code cover many factories. In practice the same listing can ship a 40 mm case on one order and a 42 mm case on the next, or a Miyota-based movement instead of a decorated clone. Ask for measurements and photos of the exact unit in stock. If the seller refuses, treat the listing as unknown quality.
Inspection steps
- Ask the seller to name the genuine reference the copy is based on, such as 210.30.42.20.03.001, and to put the movement type in writing.
- Request caliper photos of the case. Genuine 42 mm Seamaster 300M cases measure near 13.5 mm thick, so a copy that reads 14 mm or more will sit tall on the wrist.
- Photograph the bezel insert straight on. Ceramic copies should show clean white marker fill with no bleeding over the edges.
- Check the dial under angled light. The genuine wave pattern is laser engraved into ceramic, so the lines stay sharp and shallow rather than painted on.
- Look at the date window and its position against the genuine layout for that reference.
- Inspect the hands. Skeletonized hour and minute hands with a lume fill are standard, and sloppy fill shows at the tips.
- Confirm the helium escape valve sits at 10 o'clock and the crown guards are cut, not molded flat.
- Ask for a caseback photo. Look at the engraving depth, the wave edge and how the NAIAD lock text is rendered.
- Ask for a movement photo or video. Check rotor decoration, beat rate and whether the seconds hand hacks when you pull the crown.
- Check the bracelet taper and clasp. Screw links, not pushed pins, and engraved clasp text with even depth.
- Do not dive with any copy. Treat the water resistance claim as decorative regardless of what the listing says.
Tells that show up on cheap 291 units
- Bezel action that rattles or has back play when you reverse direction.
- Dial waves that look printed and flat instead of engraved.
- A date wheel with a font that is too wide or sits off center in the window.
- Lume that fades within minutes next to a known good watch.
- Caseback engraving that is shallow, fuzzy or missing detail in the hippocampus.
- Bracelet end links that do not sit flush against the case lugs.
Questions to ask before ordering
- Which factory produced this unit, and can you send photos of the actual watch in stock?
- What movement is inside, and is it automatic or quartz?
- What are the measured case diameter and thickness?
- How long is the warranty, and who pays return shipping on a defect?
- Can you show the bezel rotating and the crown screwing down on video?
Price tiers and what changes
Entry 291 copies usually run quartz movements, mineral glass and stamped clasps. Mid tier units add automatic movements, sapphire crystal and better bezel inserts. Top tier Super Clones focus on case geometry, dial engraving and movement decoration, which is where most of the visible difference lives. Spend your budget on the case and dial first. Movement decoration matters less if you never open the caseback.