Monochrome Watches
An online magazine dedicated to fine watches

The Omega Seamaster Planet Ocean 600M Dark Grey GMT, with New Silicon Nitride Ceramic Case

Strong, light and innovative, the PO 600M comes in 600 shades of ceramic and titanium.

| By Brice Goulard | 3 min read |
Omega Seamaster Planet Ocean Dark Grey

Without a doubt the most contemporary collection of dive watches by Omega, the Seamaster Planet Ocean 600M is a strong model devoted to performance, mixing luxurious elements with all the necessary features you’ll need in a deep dive watch. This highly modern intention, which separates it from the classic Diver 300M or the vintage-inspired Seamaster 300, is mostly seen in the use of innovative materials. The collection now expands with the use of an unprecedented type of ceramic, a.k.a silicon nitride ceramic [Si3N4], resulting in the introduction of this light, robust, bold and monochromatic Omega Seamaster Planet Ocean Dark Grey GMT.

Omega Seamaster Planet Ocean Dark Grey

While at first identical in design and features to the Planet Ocean Deep Black, already an oversized ceramic diver with additional GMT complication, the new Planet Ocean Dark Grey introduces a new compound for its case and other elements of the habillage, a ceramic known as silicon nitride ceramic or Si3N4. It is the first time this specific ceramic is used on such a large scale, and it’s here seen on the case, the NAIAD LOCK caseback and the bezel insert. For the occasion, the choice has been made to have an entirely monochromatic look, with the grey ceramic mixed with grade 5 titanium for the bezel body, the crown, the helium valve and the clasp (and the dial too, but more on that in a few).

Ad – Scroll to continue with article

Omega Seamaster Planet Ocean Dark Grey

This dark grey material results in a watch with a pleasantly utilitarian and discreet look, which contrasts with the overall wrist presence of this watch. Like the Deep Black GMT, this Dark Grey edition measures 45.5mm in diameter, with an unmistakable thickness of over 17mm and a length of 51.5mm. This will be compensated by the lightness of the materials used, silicon nitride being twice lighter than traditional zircon ceramic and grade 5 titanium being around 40% lighter than steel. The total weight is 107 grams, while a classic black ceramic version is 140 grams and a steel PO 600m GMT on a steel bracelet weighs 226 grams.

The case is otherwise classic PO 600m, with lyre lugs, a unidirectional bezel with a 60-minute scale (so despite the GMT function, it remains a real dive watch), sapphire crystals front and back a helium valve at 10 o’clock and a screw-down crown, all for a robust 600m water-resistance.

Omega Seamaster Planet Ocean Dark Grey

The dial of the Planet Ocean Dark Grey is, as you’d expect from the name, executed in the same tones. In fact, following the lightweight intention, it’s made of solid titanium with a sandblasted finish. The anthracite-coated hands and indexes bring continuity to the look, while the generous amount of white SLN is here for legibility night and day. Orange accents on the dial and hands bring the necessary dosage of fun. This true GMT watch (flyer/traveller style) features a 24-hour inner bezel to keep track of an additional time zone.

Omega Seamaster Planet Ocean Dark Grey

Turning the watch over, you’ll discover that the well-known calibre 8906 has changed quite a bit… Indeed, just like the rest of the watch, it’s all about lightness and robustness, with bridges and plates made from matte-treated grade 5 titanium. Apart from this dark aesthetic and new material, the movement is identical to previous editions, with its Master Chronometer certification, its antimagnetic properties, its co-axial escapement and a dual-barrel architecture for 60h of power reserve.

Omega Seamaster Planet Ocean Dark Grey

Worn on an integrated rubber strap with grey textile inlay, and closed by a titanium folding clasp, the new Omega Seamaster Planet Ocean Dark Grey GMT is an impressive model with high-end technology, which comes at an equally impressive price of EUR 24,500. It’ll be part of the permanent collection. For more details, please visit

3 responses

  1. What is the accuracy of the Calibre 8906ti – in-house – Master Chronometer ?

  2. @Graham – like all Omega Master Chronometer watches (except the new Spirate watch), this one has a claimed accuracy between 0 and +5 seconds per day.

  3. The OMEGA SEAMASTER PLANET OCEAN 600M CO-AXIAL MASTER CHRONOMETER GMT 45.5MM DARK GREY is interesting with several caveats: Why in hell would anyone diving 600 meters would want to know the time in Greenwich England? 2. Why does OMEGA continue to have a valve release sticking out like a Mickey Mouse ear when 99.9 percent of the people who purchase this watch will never dive more than 20 feet. Last: The materials used for this watch are very interesting if the watch is made in 37 or 38mm and without the ridiculous helium valve at ten o’clock…..and, who cares if the watch has a chronometer rating since any watch regardless of cost is able to be regulated. Case in point. I own a Baltic none chronometer dive watch which only gains one or two seconds per day.


Leave a Reply