Short answer

Omega builds the Seamaster 300 in a 41mm case. Watches sold as "1:1 replica" or "first copy" versions of it are counterfeit goods. They carry no Omega warranty, no METAS Master Chronometer test record, and no service support. Import into the United States is barred by 19 U.S.C. 1526, and U.S. Customs and Border Protection seizes shipments at ports of entry.

Genuine 41mm Seamaster 300 specs

  • Case diameter: 41mm, measured across the bezel without the crown
  • Lug width: 21mm
  • Water resistance: 300m
  • Crystal: domed sapphire, with a sapphire caseback on most references
  • Bezel: ceramic insert with a Liquidmetal dive scale on steel references
  • Movement: calibre 8400 (no date), 8401 (titanium), or 8912 (date, Master Chronometer)
  • Magnetic resistance: 15,000 gauss on Master Co-Axial and Master Chronometer versions

Reference numbers change with case metal, dial, strap, and bracelet. A short number alone does not identify a watch. The full reference does.

What replica listings contain

Counterfeit 41mm Seamaster 300 watches use third-party movements, not Omega calibres. Case finishing, plating thickness, and gasket material differ from the genuine part. Water resistance is not pressure tested, so a 300m claim on a counterfeit is a claim, not a measurement. Serial numbers are copied or invented, which fails any check against Omega records.

Checks that apply to any 41mm Seamaster 300

  1. Measure the case across the bezel, crown excluded. Genuine: 41.0mm.
  2. Measure lug spacing. Genuine: 21mm.
  3. Read the movement through the caseback. Calibre 8400 has no date window. Calibre 8912 has a date at 3 o'clock.
  4. Check the METAS Master Chronometer card on 8912 versions. The card holds the movement serial and test results.
  5. Request service records from an Omega service center. Genuine watches have them. Counterfeits do not.

Legal position

Counterfeit watches infringe Omega trademarks. 15 U.S.C. 1114 covers trademark infringement in commerce. 19 U.S.C. 1526 bars import of goods bearing a counterfeit mark. CBP publishes seizure statistics for watches each year. Buyers of counterfeits hold no recourse for defects, seizure, or resale.