Omega Seamaster 300M 36mm Ref 2551.80 Full Set 1999 Watch

Q: What is the Omega Seamaster 300M 36mm Ref. 2551.80 (1999)?
A: It’s the mid‑size version of Omega’s iconic Seamaster Professional Diver 300M, featuring a 36mm stainless steel case, blue wave dial with luminous hands/markers, a unidirectional blue bezel, screw‑down crown and the signature helium escape valve at 10 o’clock. This example is from 1999 and comes as a full set with original box and papers.

Q: Which movement does this reference use?
A: Most Seamaster 300M models from this era house Omega’s automatic chronometer calibre (often the Calibre 1120, based on the ETA 2892‑A2) with a quickset date. If you’d like us to confirm the exact calibre in this specific watch, please contact us.

Q: Is it water‑resistant and can I swim or dive with it?
A: The Seamaster 300M was originally rated to 300 metres, but water resistance on vintage watches is not guaranteed without recent servicing and pressure testing. We recommend avoiding swimming or diving unless the seals have been replaced and the watch has been pressure‑tested by a qualified watchmaker. Always keep the crown fully screwed down and never open the helium valve underwater.

Q: How do I set the time and date, and operate the crown?
A: Unscrew the crown anti‑clockwise. Position 1 (pushed out lightly): manual wind (20–30 turns if the watch has stopped). Position 2: quickset the date. Position 3: set the time. Avoid changing the date between approximately 8pm and 2am to protect the mechanism. When finished, push the crown in and screw it down firmly.

Q: What does the helium escape valve do and when should I use it?
A: The valve is designed for saturation diving to release trapped helium during decompression. It should remain closed for everyday wear and all normal aquatic activities. Only trained divers should use it; never operate the valve underwater.

Q: Does this model have a sapphire crystal and what is the bezel made of?
A: Yes, the Diver 300M from this era typically features a scratch‑resistant sapphire crystal. The blue bezel insert is aluminium on 1990s models (later modern iterations moved to ceramic). Luminous material is appropriate to its production period; we can confirm specifics on request.

Q: How does the 36mm mid‑size wear, and is it unisex?
A: The 36mm case offers a balanced, classic profile suited to small‑to‑medium wrists and those who prefer a discreet diver. It is widely worn unisex. If you’d like fit advice, share your wrist measurement and we’ll help.

Q: Can the bracelet be resized or swapped for a strap?
A: Yes—the steel bracelet can be sized, and additional links can often be sourced (subject to availability). The mid‑size 300M commonly uses an 18mm lug width; quality straps (rubber, leather or NATO) that match the correct lug width will fit. Contact us for sizing or strap recommendations.

Q: What accuracy and service interval should I expect?
A: As a chronometer, the calibre was designed to keep time to COSC standards. Actual performance varies with age and service history. A routine service every 5–10 years is generally recommended, or sooner if there are timekeeping or water‑resistance concerns. Keep the watch away from strong magnets and have it checked if you notice running fast/slow or condensation.

Q: What is included, and how do you guarantee authenticity?
A: This piece is delivered as a full set (original box and papers). A Retro Tale thoroughly inspects and authenticates every item and provides a 12‑month mechanical guarantee. We’re happy to share additional photos or confirm movement and reference details upon request.