Short answer

A fake Omega Seamaster 300 Master Chronometer copies the outside of the watch. It cannot copy the movement or the METAS certificate. Check the sapphire caseback, the crown, the bezel action, and the METAS card. A genuine watch runs a Co-Axial calibre 8400 or 8912 with a silicon balance spring, a 60-hour power reserve, and resistance to 15,000 gauss.

What the real watch is

Omega launched the Seamaster 300 Master Chronometer in 2014 as reference 233.30.41.21.01.001. The case measures 41 mm, is steel, and is water resistant to 300 m. Calibre 8400, no date, 60-hour reserve. The 2021 update uses calibre 8912 with the same 60-hour reserve and a sapphire caseback. Each Master Chronometer passes an 8-test METAS protocol across 10 days. Average daily rate must stay between 0 and +5 seconds.

Checks that catch most fakes

  • Caseback: laser engraving is sharp with even depth. Fakes show shallow, rounded letters and a soft hippocampus.
  • Sapphire back: the movement is visible. Fakes use a Miyota 9015, Seiko NH35, or a decorated Chinese clone.
  • Balance wheel: on a real 8400 it sits under a full bridge. An open balance in a Seamaster 300 is wrong.
  • Crown: threads engage in under two turns and the logo is crisp. Fakes feel gritty and the stem wobbles.
  • Bezel: 120 clicks, no back play. Fakes skip and drift.
  • Case size: 41 mm wide, 13.9 mm thick. Many fakes run 1 mm larger.
  • Date window: none. A date at 3 o'clock is wrong for this model.
  • METAS card: carries a unique number that matches the movement and case.
  • Serial: 8 digits stamped on the lug at 7 o'clock, not etched.

Movement numbers

Calibre 8400 beats at 25,200 vph, or 3.5 Hz. Calibre 8912 beats at 25,200 vph. A 28,800 vph sweep on a timegrapher points to a counterfeit movement or a swap. Magnetic resistance of 15,000 gauss comes from non-ferrous parts, so a strong magnet should not stop the balance.

Price and paper

Used prices for a genuine Seamaster 300 Master Chronometer ran $3,400 to $5,200 in 2024, based on condition and box. Counterfeits sell for $80 to $400. A listing far under market with no METAS card or warranty card points to a counterfeit or a parts watch.

What photos cannot show

Thread pitch, gasket condition, and lume application need the watch in hand. A photo cannot show the click feel of the bezel or the drag of the crown. Sales photos also hide movement swaps and aftermarket dials. Ask for a timegrapher photo, a METAS card photo, and a caseback photo shot at an angle. Unknown sellers often skip one of the three.