News: Grand Seiko 60th Anniversary Limited Edition Professional Diver’s 600M Featuring the new Spring Drive caliber 9RA5 movement by Robert-Jan BroerMarch 05, 2020 MIN READNews: Grand Seiko 60th Anniversary Limited Edition Professional Diver’s 600M
Despite the cancellation of Grand Seiko’s summit, the new watches are being introduced anyway (kudos for that). Thus, we’re kicking off with the new Grand Seiko 60th Anniversary Professional Diver’s 600M.
That’s right, Grand Seiko was born in 1960 and celebrates its 60th anniversary this year. Not exactly the celebration they had in mind in Japan, but I am sure we will get an opportunity to see the watches live and to test drive them. For now, we’ll have to make do with the press releases they’ve shared with us.
Grand Seiko 60th Anniversary Limited Edition Diver’s 600M
This watch might look familiar to you. It looks similar to the Grand Seiko Diver SBGA231G (that I reviewed here) or perhaps better said, to the SBGH255 and SBGH257. While the SBGA231G is a bit smaller (and “only” water-resistant to 200 meters), it does have a Spring Drive movement inside. The SBGH255 has a few more similarities to this new 60th Anniversary Limited Edition Diver’s 600M. It is a bit larger with its 46.9mm High-Intensity Titanium case, and it has a Hi-beat movement. A picture of the SBGH257 from 2017 can be found below.
Grand Seiko Hi-Beat 36000 Professional 600m Diver SBGH257
A few more differences
Although the new Grand Seiko Diver (SLGA001) watch looks very similar to the 2017 models (like the above), there are — besides the dial — a few more differences of course. For starters, the new Grand Seiko 60th Anniversary Limited Edition Professional Diver’s 600M features the brand new Spring Drive caliber 9RA5 movement. This new kid on the block boasts a whopping 120 hours power reserve. This generous run time is courtesy of a dual-barrel system. Unusually, the barrels are of different sizes. This enables them to generate the required torque while remaining compact enough to fit inside this new, slimline Spring Drive caliber.
Spring Drive Caliber 9RA5
But it is more than just more power reserve. To celebrate its 60th anniversary, Grand Seiko developed this new movement to become slimmer and more accurate than the other Spring Drive movements. Its monthly precision rate has improved from ±15 seconds a month to ±10 (and ±0.5 per day). The thickness of the movement has been reduced from 5.8mm to 5.0mm and the speed of the date change increased.
The reduction in thickness of the movement also results in a thinner watch (than the 17mm SBGH255 and SBGH257 for example). This new Grand Seiko Diver reference SLGA001 has a thickness of 16mm. Ok, that’s still not a very thin watch. But considering the 600m depth rating, that’s pretty impressive. I’m sure we’ll find this one on the wrist of many a saturation diver, who are often required to work at such depths.
(Grand) Seiko has been using the Magic Lever since 1959…
Grand Seiko’s movement designers reduced the size by repositioning the Magic Lever construction. (Grand) Seiko has been using the Magic Lever since 1959 and it is a clever system that boosts the efficiency of the self-winding mechanism by using the energy created by the bi-directional winding of the rotor. For the Grand Seiko caliber 9RA5, the (Offset) Magic Lever is not positioned in the center anymore, as the new name implies. This helps to reduce the thickness of the movement. Additionally, the winding efficiency remains unaffected by this new configuration.
But wait, there are more 60th anniversary treats in store. Despite the slimness of this movement, Grand Seiko enhanced the shock resistance of it by adopting a new gear train layout. A central bridge (One-Piece Center Bridge) holds them all together, making it more rigid and achieving a shock resistance that meets the ISO standard for divers’ watches. Grand Seiko shared a drawing with us on what this new construction looks like.
Last but not least, Grand Seiko upgraded the IC. It is now equipped with a sensor to measure the temperature changes inside the movement and compensate for any inaccuracies because of these in the oscillation rate. Both the oscillator and sensor are vacuum-sealed into one package, to reduce possible external influences. Everything is done to maintain the highest possible accuracy of the movement, and the results are quite amazing (+/–0.5 seconds per day).
As you can read, the SLGA001 is a very technical watch, hi-tech, I’d say. Not only the Spring Drive caliber 9RA5 movement but also the use of the brand’s high-intensity titanium for the case and bracelet. This material is 40% lighter than stainless steel. It is also more resistant to scratches, which somehow always look worse on titanium and on steel. At least that’s from my own experience of wearing titanium watches. The case construction is helium valve-free for use by saturation divers, and the high-definition sapphire crystal ensures clear vision on the dial under almost all circumstances.
The finish on the case, bracelet, dial, hands, etcetera is as good as we’ve come to expect from Grand Seiko. There’s a reason we’ve been raving about in all these years. It’s simply stunning. There will be only 700 of these Grand Seiko 60th Anniversary limited edition Diver’s 600M watches. It retails for €11,500 including VAT. It will be delivered in a Grand Seiko 60th Anniversary box and includes an additional blue silicone strap. We can’t wait to go hands-on with this new Grand Seiko reference. And since it is the 60th anniversary, there are loads more releases to come! Stay tuned. More information via Grand Seiko online.
Brand Grand Seiko Model60th Anniversary Limited Edition Diver's 600MReferenceSLGA001DialBlackCase MaterialHigh-intensity titaniumCase DimensionsDiameter: 46.9mm, Thickness: 16mmCrystalHigh definition sapphireCase BackScrew-inMovementCaliber 9RA5, Self-Winding (Spring Drive), Power Reserve: 5 daysWater Resistance600 metersStrapHigh-intensity titanium bracelet, blue silicone strap.FunctionsTime, Date, Power Reserve, Diving BezelPrice€11,500WarrantyThree years of international warrantySpecial Note(s)Limited to 700 pieces worldwide, available in August Watch of the Week
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About the author
Ever since he was a young child, Robert-Jan was drawn to watches, even though it were digital Casio and quartz Swatch models at the time. In the mid-1990s, his interest increased when he started to read about mechanical watches in… read more
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