Review: Seiko Prospex SNR031J1 LX Black Edition Dive Watch

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Seiko introduced the new LX line of Prospex watches in Baselworld 2019 with the usual three categories of Land, Sea and Air. The new line features several watches in each, and all equipped with their legendary Spring Drive movements. We examine the Sea offering of the SNR031J1 LX Black Edition Dive Watch in detail in this article.

See also our Live from Baselworld 2019: Seiko coverage. And also the Seiko announcement page.

The Seiko Prospex LX line

The Seiko Prospex LX line was developed in collaboration with Ken Okuyama Design. Okuyama formerly worked for Pininfarina, and led the design of the Enzo Ferrari and Ferrari P4/5. He was also involved in the design of the Japanese Shinkansen trains. Okuyama brought his creativity and his modern elements of design to create this new collection of watches, which “take the unique inheritance and integrity that Seiko has built in sports watches over the decades and to bring them alive in a design that has simplicity, harmony, power and presence“.

The watches are lined up as diving, compass and GMT, each corresponding to what Seiko sees as the main activity in each of the categories. The design is derived from the 1968 Professional Diver re-issued with a high beat movement in Baselworld 2018 as the SLA025. As mentioned the LX series will carry Spring Drive movements. All the watches are in titanium in two versions – one a bright titanium standard edition, and a special series of three all-black interpretations. All six watches will be available at selected Seiko Boutiques and outlets around the world in July 2019.

Seiko Prospex SNR031J1 – LX Black Edition Dive Watch

We focus on the LX Black Edition and the Dive watch.

The case, dial and hands

The case is a rather large 44.8mm diameter, but despite the dimensions, it sits comfortably on the wrist. The design concept of the case shape is to allow the watch to wrap around the wrist in an organic way. The entire center of gravity of the case is set low to to allow the watch to be more comfortable on the wrist. And the case shape is faceted along many angles to accentuate the zaratsu polished surfaces.

The case is depth tested and rated to 300m and according to Seiko is suitable for saturation diving. As is normal for Seiko saturation diving watches, the case does not use a helium escape valve, but depend on the structural integrity of the case design to prevent popping the crystal during de-compression.

The watch also features a magnetic resistance rating to magnetic fields up to 4,800 A/m. A quick calculation shows that this magnetic field has a flux density of about 60 Gauss. From our discussions with experts, this is sufficient for almost all diving requirements. As a trivia comparison, the Earth’s magnetic flux density ranges from 0.25 to 0.65 gauss, while on the other extreme, the magnetic flux of the lattice magnets within the CERN Large Haydron Collider is about 99,000 Gauss and Omega tests their Master Chronometer to withstand flux densities of 15,000 Gauss.

Stripped of all color and reduced to its essentials, the simplicity and strength of the Black Edition is quietly dramatic. The case is treated with a black super-hard coating and the flat surfaces are Zaratsu polished. The sea version is offered with a silicone strap.

The infill on the engraved markers and numerals on the bezel is a faint blue, which almost merges into the black ceramic, but not quite.

The dial layout is de rigueur for a diving watch, with large, luminous hands, and huge hour markers. Legibility is excellent both in the dark and in light. Also standard is the uni-directional bezel which is huge and easy to operate.

The movement: Seiko caliber 5R65

As is typical for a dive watch, there is no display case back, but the Prospex LX features a screw down back. Within is Seiko’s Spring Drive caliber 5R65. This is not a new movement from Seiko, and has seen service in the Marinemaster Prefessional 600.

We expect the usual finese in finishing found in Seiko Spring Drive movements to be used on the 5R65. This means that the finishing will be at a very high level of engineering finish. Spring Drive movements are assembled in Seiko’s Shinshu Shiojiri manufacture. Details of the manufacture and a view of how these movements are created is found in this link.

The 5R Spring Drive caliber offers one-second a day precision alongside high levels of shock and temperature resistance. With these attributes, 5R is a good choice for sporting and adventure. It has been worn successfully both in space, when it travelled to the International Space Station and was worn on a space walk and at the top of the world, when Yuichiro Miura wore a Spring Drive watch on his third successful ascent of Mount Everest.

The competitive landscape

At € 6,100 (equivalent to approximately S$ 9,333), the Seiko is not inexpensive. But it is beautifully crafted and incredibly robust. The competitive landscape of diving watches with 300m depth rating is as populated as the trees in a forest. There are perhaps too many to elucidate,. Only a few exist in a titanium case, and none, safe for Seiko’s own creations, will bear a Spring Drive movement. But for purposes of brief comparison, here are a few considerations:

Omega Seamaster Professional SMP 300m. (S$ 6,750 in a rubber strap and S$ 7,200 in SS bracelet), comes with a beautifully crafted ceramic dial with a wave motif, and a ceramic bezel on a stainless steel case.

The Omega Seamaster Professional SMP 300m. The line is updated this year in Time to Move with a magnificent Chronograph model. Full review soon.

The Omega is also designed for saturation diving, but has a manually activated crown to serve as the helium escape valve at 10. The Seamaster Professional SMP 300m is METAS certified.

Rolex Submariner Ref. 114060 or the Ref 116610, is a possible competitor, if one can get one’s hands on one at the retail price of S$10,030 or S$11,440 for the version with date.

The Rolex Submariner, Ref 1140460. Better known as the “No Date” Submariner.

The Rolex is also in a stainless steel case, and rated to 300m, but not for saturation diving. Rolex, of course uses their in-house caliber 3100 (or 3135 with date) movement which is well proven to be superbly robust, and accurate. And of course, the resale value of the Rolex is beyond any Seiko.

Concluding thoughts

Overall, this is a very satisfying watch to strap on one’s wrist, even if its only for the pleasures on dry land. The Seiko Prospex LX Black Edition Diver is exceptionally well crafted with handsome good looks and a robustness that often exceeds that of the owners. The titanium case is very strong and hardy. And in the Black Edition guise, quite stealthy. The Spring Drive movement is second to none, and one can entertain oneself endlessly by watching the seconds hand move silently and smoothly across the dial. Frankly, the dial is rather beautiful to set one’s gaze on as well.

But take it under water, and it still shines for all duties it is required to perform, be it swimming, scuba diving or even professional saturation diving.

In the light titanium version the watch is delivered with a matching titanium bracelet. The overall look of this version is somewhat less menacing at the same time less stealthy than the Black Edition we review here.

The watch is rather large, and if one’s wrists (and cuffs and dress sense) can pull it off, it is a magnificent example for the daily beater.



  1. You had an SD movement that lost 90secs a week? Also, I think you mean CNC machine. Every watch produced these days needs a CNC for at least part of the manufacturing…

    I will gladly be “the next guy” to have this watch. Not sure the watch you’re banging on about.

    • Agree. If the SD loses 90s a week, something is wrong with it. It needs to be serviced.

      And yes, almost all watch parts are made with CNC machines these days. But SD movements are not assembled by robots. They are hand assembled, as are most high end watches.

      Grand Seiko SD are of course much better finished. But a different price point and a different kettle of fish.

  2. An old movement intended to move old stock and parts. Prospects has the kind of finished that makes you regret you did not wait til you could afford a Grand Seiko. I had one for a month and regretted it so I am saving for a GS .

    They make great inexpensive watches made by robotic CBC machine. Prosepex is intended to fill the market space between. Mine lost 90 seconds a week. Now the next guy can deal with its inferior performance. Wish him well I do