The term “Master Co-Axial” refers to the new in-house Omega Co-Axial Master Chronometer caliber 8912.

The automatic movement uses a free-sprung balance with a silicon balance spring having two barrels mounted in series. Antimagnetic properties make it resistant to magnetic fields reaching 15,000 gausses. Rounding out the specs, 38 jewels running at a frequency of 3.5 Hz with a beefy 60-hour power reserve, and a traversing balance bridge that reduces negative effects from impacts compared to a single-arm bridge.

Omega Seamaster 300 Co-Axial Master Chronometer Bronze Gold

As for the coaxial master chronometer certification, a Master Chronometer label is given to a watch that has undergone testing and received a certificate from the Official Swiss Chronometer Testing Institute, the Contrôle Officiel Suisse des Chronomètres (COSC), the institute responsible for certifying the accuracy and precision of Swiss watches. Furthermore, it is Master Chronometer certified, guaranteeing the Swiss industry’s highest standard of precision, performance, and magnetic-resistance, as set by the Swiss Federal Institute of Metrology (METAS). Whew.Omega caliber 8912 Seamaster 300 caseback

Omega premiered the Seamaster 300 in 1957. It was touted as a watch designed for divers and underwater professionals. Sixty-four years later the Seamaster collection has been completely upgraded by Omega and includes this model for review.

Omega Seamaster 300 Co-Axial Master Chronometer Bronze Gold

The Seamaster 300 Co-Axial Master Chronometer 41 mm Bronze Gold Ref. has a retail price of $11,600.00 (gulp). The steel Omega Seamaster 300 models start at $6,500. Uniquely, the Bronze Gold Seamster 300 is made with Omega’s very own bronze alloy, coined 9K Bronze Gold. Significant research and development went into this material, an alloy of up to 37.5% gold while also containing copper, silver, and palladium. This gives the metal a pink hue, corrosion resistance without verdigris-oxidation which is the green pigmented patina sometimes seen when copper, brass, or bronze is exposed to air or seawater over time (think the Statue of Liberty) and will therefore age more slowly.

Omega Seamaster 300 Co-Axial Master Chronometer Bronze Gold

The case diameter is a wrist-friendly 41 mm and uses a unidirectional rotating bezel. The bezel ring is made of brown ceramic, often looking black, with a diving scale and vintage color-inspired luminous markings. The sandwich dial uses a bronze alloy (CuSn8) to offer a unique dark brown color (again often looking black) with a surface created after a special aging process. The hour markers are recessed and at six and nine o’clock open Arabic numerals are present, all reminiscent of the vintage Seamaster 300’s we know and love. The hands are PVD Bronze Gold colored and vintage-inspired patina colored lume is used on the dial and hands, matching the bezel. Interestingly, however, the minute hand and pip of the bezel fluoresce with a different color (green) than the indices, hour hand, and rest of the bezel markers (blue).

Omega Seamaster 300 Co-Axial Master Chronometer Bronze Gold

Always an odd choice, lug width is a mystifying 21 mm although the manufacturer-supplied brown leather strap (21 mm tapering to 16 mm with a signed 9K Bronze Gold pin buckle) is extremely nice, however. The crystal is a domed, scratch‑resistant sapphire with an interior anti-reflective treatment. The sapphire caseback screws down to the case, and so does the crown. Water-resistance is a true professional dive watch worthy rating of 300 meters.

Omega Seamaster 300 Co-Axial Master Chronometer Bronze Gold

For me and my sub-7-inch wrist, the 48 mm lug-to-lug width is slightly longer than my comfort zone but I expect anyone with a 7-inch wrist or greater will find it a really nice fit. Case thickness including crystal is 13.8 mm and weight on the leather brown leather strap weighs in at 100 grams.


Overall, it’s hard to say this isn’t a great dive watch. I mean, it has the certifications to back it up. I don’t know if I want it in a patina-forming material but the differences between Omega’s 9K Bronze Gold and the materials I have owned previously experienced make it very interesting. Collectors have their feelings about faux patina-colored lume but I find it works at times (more often than it doesn’t in my opinion although I think I’m in the minority there) and here, I like it. Playing with the pinkish hue of the gold bronze case and the sandwich brown/black dial it makes sense. I, as usual, would love 1-2 mm less lug to lug but I need to hit the gym. Finally, the elephant in the room, is the sticker price. You think master coaxial-coaxial master chronometers come cheap? Guess again. If you want a modern diver that is dual-certified and 300 meters rated from a luxury brand that you can actually locate and buy, this might be the one for you. For now, I’m ok with my vintage SM 120 with Caliber 565 (no certifications but 24 jewels, 2.75Hz, 50-hour power reserve), but I have no dive plans anytime soon.

The retail price is $11,600.

Learn more at Omega.

Omega Seamaster 300 Co-Axial Master Chronometer Bronze Gold



Seamaster 300 Co-Axial Master Chronometer 41 mm Bronze Gold


Year: 2021

Total Weight: 100 grams

Case Diameter: 41 mm

Case Thickness: 13.8 mm

Lug-to-Lug: 48 mm

Lug Width: 21 mm

Posted by:Brett K.

Orthodontist by day, watch collector 24/7, 💯 handheld photography.