Omega Seamaster Diver 300M Co-Axial Master Chronometer

Time to do a review of the new Omega Seamaster Diver 300m Co-Axial Master Chronometer Chronograph. Let’s dive right in.

We’ve written arguably the most detailed and transparent reviews about Seamaster watches on the web. Now it’s time that we do the same for the Omega Seamaster Diver 300m Co-Axial Master Chronometer Chronograph.

The Omega Seamaster has been synonymous with diving and excitement since its inception and many Seamaster watches have come into existence following the success of the original Seamaster.

This is what happens when a successful watchmaker like Omega perfects a watch to the point where the only way to make it better is to add mechanical features such as a Chronograph which gives the watch a stopwatch function.

Let’s get up close and personal with this watch. While we can find models in this collection that have rubber straps, two-tone bracelets, and even one with an 18kt rose gold case, today we’ll be looking closely at two of the most popular models in this series. Let’s dissect the watch spec-by-spec, shall we?

The dial of the Seamaster Professional Diver 300m has always had a very distinct look. Recently, since the Master Chronometer designation has been given to this collection, the dial now has a laser engraved wavy pattern. This is currently found on both the new Seamaster Diver 300m Co-Axial Master Chronometer and the Chronograph version of this watch.

A combination of round and index luminous appliqué hour markers circle dial and skeletonized polished steel hands have luminescent material for maximum legibility in low light conditions.

On the new Seamaster Chronograph models, the printed second’s track also has split seconds printed between each second’s marker. This, of course, is to allow for precise timing with the chronograph.

Two sub-dials are found on the dial. The small running seconds sub-dial can be found at the 9 o’clock position and on the right is the 12-hour chronograph sub-register. Both sub-dials have polished steel hands with a small amount of luminous fill.

A date window is at the 6 o’clock position of the dial which is controlled by the winding crown on the right side of the case.

The Omega Seamaster Professional branding can be found on the top of the dial just beneath the applied 12 o’clock double index hour marker. The words “Co-Axial Master Chronometer 300m/1000ft” can be found printed just above the date window at the 6 o’clock position. The dial is made of a high gloss zirconium oxide ceramic and therefore [ZrO2] is engraved on the sapphire crystal covering the dial just beneath the center hands.

The cases on these two models use a combination of polished and brushed stainless steel.  The lugs are polished on the outer angles and use a brushed finish on the front-facing facets. The crown guards use a polished finish as do the screw-down crown and chronograph pusher sleeves.

A polished helium escape valve is on the left side of the case at the 10 o’clock position. This is used to allow tiny helium molecules to escape from the inside of the case. These tiny helium molecules are so small that they can naturally make their way through the case and crystal and they build up when diving using a diving bell. The Helium escape valve allows you to release them once on dry land.

The bezel on these two models is made of stainless steel and is filled with a hardened scratch-resistant ceramic fill. Enamel numerals and indices are then added around the bezel. At the very top of the bezel is a luminous dot at the start point. This bezel is a bit of an upgrade from previous Seamaster models. It is more grippy and has a smoother action to it and gives off less of a ratcheting clicking sound when rotating.

The chronograph uses a column-wheel design instead of a cam-actuated design allowing for smoother movement and starting and stopping action. It is operated via the chronograph pushers which, as mentioned earlier in this review, are located on either side of the crown on the right side of the case.

On the blue model, the chronograph pushers are made of ceramic material and are shaded blue to match the dial and bezel. Similarly, on the black model, the pushers are black to match. These pushers use screw-down “sleeves” to keep water out of the case.

The stopwatch feature can be initiated by pushing the top pusher button. When pushed, the large central chronograph seconds hand on the dial with begin to rotate. Push the button again to stop the chronograph and push the bottom button to reset the stopwatch.

The bracelet uses a multi-link design with a brushed wide central link and outer links and inner links that use a combination of brushed and polished finishes. The bracelet is built solid and is fastened with a push-button folding clasp. Furthermore, the bracelet has a feature that allows micro-adjustments to be made to the bracelet size with the push of a button.

The heartbeat of the watch comes from the in-house Omega Master Chronometer caliber 9900 and oscillates at a rate of 25,200 vibrations per hour. The Omega 9900 automatic movement contains 54 jewels and uses a magnetic resistant silicon balance-spring. Thanks to the double barrels which are mounted in series, this self-winding movement features a generous 60-hour power reserve.

This beautifully finished movement can be seen in action through the transparent sapphire case back. The 9900 caliber uses Geneva waves in an arabesque pattern for the finishing technique and more importantly, is a METAS certified Master Chronometer.

This means that the caliber had to first be tested by COSC and receive the COSC chronometer designation after achieving a minimum level of precision of only -4/+6 seconds per day in deviation. After being regulated and passing these tests and receiving a COSC certificate, the caliber is then sent to another lab called METAS.

METAS then tests the watch for several other things including minimum advertised water resistance and magnetic resistance to electromagnetic fields up to 15,000 Gauss. It is then regulated once again only this time to achieve a minimum precision of -0/+5 seconds per day which is even more precise than a prestigious COSC chronometer! Then and only then, does the watch receive Omega’s Master Chronometer designation. Arguably one of the world’s most hard-to-beat marks of excellence in mechanical watchmaking precision and accuracy.