Short answer

The number 512 does not appear in Omega's current reference format for the Seamaster Diver 300M. Genuine references use dotted groups, for example 210.30.42.20.01.001. A listing that advertises a "512 version" is using a seller code, not a factory code. Judge the watch by four parts: movement, caseback, dial, and bezel. Ask for the full reference and the 8-digit serial before you pay.

phony omega seamaster 300m 512

Genuine specs to compare

  • Case: 42 mm steel, 13.6 mm thick, 20 mm lug width.
  • Water resistance: 300 m. Helium escape valve at 10 o'clock.
  • Movement: Co-Axial Master Chronometer calibre 8800. 25,200 vph. 55 hours of power reserve. Free-sprung balance with no regulator index.
  • Certification: METAS Master Chronometer. Accuracy range of 0 to +5 seconds per day. Magnetic resistance to 15,000 gauss.
  • Dial: ceramic with laser-engraved waves on 2018 and later models. Date at 6 o'clock.
  • Caseback: sapphire display back with a wave-edge rotor on 2018 and later models. Solid steel casebacks belong to older references.

Tells on counterfeits

  • Beat rate. Put the watch to your ear or use a timegrapher. A 21,600 vph movement ticks 6 times per second. Calibre 8800 ticks 7 times per second. Many fakes run a Seagull ST2130, an ETA 2824 clone, or a Miyota 8215 at 21,600 vph.
  • Balance bridge. The genuine 8800 has no regulator arm and no index screw. Clone movements show a regulator lever and a stud carrier.
  • Caseback. A solid caseback on a 2018 or later reference is a mismatch. Those references ship with a display back.
  • Helium valve. On many fakes the valve is a fixed crown. It does not unscrew and it does not seal.
  • Date window. Genuine date sits at 6 o'clock on the 2018 model with a white-on-black wheel. Fakes show a tilted wheel or a wrong font.
  • Bezel lume pip. The pip sits at the center of the triangle at 12 o'clock. Off-center pips and rough insert edges show up on fakes.
  • Crystal. Genuine sapphire carries anti-reflective coating on both faces. The dial reads clear from a side angle. Single-face coating shows glare.
  • Serial. Genuine serials hold 8 digits and match the warranty card. Fakes reuse one serial across a batch.

Price and market signals

US retail for a new Seamaster Diver 300M on a steel bracelet sits above $6,000. Listings at $400 or $700 are not genuine. A used genuine from 2018 to 2022 trades near $3,000 to $4,500. A seller who hides the reference, blocks caseback photos, or offers no return window adds risk.

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Checklist

  1. Ask for the full dotted reference and the serial.
  2. Ask for a photo of the movement through the caseback.
  3. Count the beats per second, or run a timegrapher.
  4. Match the caseback type to the reference year.
  5. Check the date position and the date font.
  6. Compare the weight against a known genuine example.

What 512 means

There is no published definition for 512. Sellers use numbers to mark restocks. The number changes with each batch. It carries no serial value and no factory record. Ask for the movement model, the case material, and the return window instead.

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