Short answer
512 is not an Omega reference number. Omega references for the Seamaster Diver 300M follow the 210.30.42.20.xx.xx.xx pattern, such as 210.30.42.20.01.001. The 512 tag appears in seller titles, batch names, and store SKUs. It says nothing about the watch itself. Ask for the caseback text, the reference number, and the serial before you judge a listing.
What the 512 tag covers
Replica sellers use short numbers to label batches and factories. A 512 label can mean:
- A production batch from one factory
- A store SKU that changes when stock is restocked
- Filler text added to match search terms
Two listings with the same 512 tag can hold different watches. Photos are the evidence that counts.
Case and dial checks
The current 42 mm Seamaster Diver 300M has a helium escape valve at 10 o'clock and a crown at 3 o'clock. The dial is ceramic with laser-engraved waves. The date sits at 6 o'clock. The bezel insert is ceramic with a white enamel diving scale. Copies miss details here: shallow wave grooves, printed bezel numbers, a date window with sharp edges, or a helium valve that sits off the case flank.
Movement checks
The genuine watch runs the Calibre 8800, a Master Chronometer movement. It beats at 25,200 vibrations per hour, which is 7 beats per second, and carries a 55-hour power reserve. It uses a silicon balance spring and resists magnetic fields to 15,000 gauss. Copies use decorated automatic movements or clone calibres. A smooth 7-beat sweep is a start, not proof, because high-grade clones copy the rate. Rotor engraving and finish under the balance wheel are harder to fake.
Serial numbers and cards
Omega engraves the serial on the lug at 7 o'clock and on the movement. The number on the card must match both. A Master Chronometer card carries the METAS test result, and the watch should keep time within 0 to +5 seconds per day. Copies reuse one serial across units. Search the number before you buy. Duplicate serials across listings point to a copy.
Water resistance
The genuine watch is rated to 300 m and tested at the factory. Copies are not. Do not swim with a replica, and do not accept a depth claim without a pressure test report.
What to ask a seller
- Full reference number and caseback text
- Serial on the lug and on the movement, in one photo
- Movement photos with the caseback removed
- Card images, front and back
- Return policy in writing
Price context
Omega lists the steel 42 mm Seamaster Diver 300M around $6,000 USD. Replica sellers quote $300 to $600. A genuine watch at a fraction of retail, or a 512 batch claim with no reference number, is a warning sign.