The Grand Seiko Tentagraph SLGC001 – the first fully mechanical chronograph movement from GS The Grand Seiko Tentagraph SLGC001 – the first fully mechanical chronograph movement from GS

The Grand Seiko Tentagraph SLGC001 – the first fully mechanical chronograph movement from GS

Zach Blass
  • Grand Seiko Tentagraph SLGC001 marks the first-ever fully mechanical chronograph from GS
  • Tentagraph stands for TEN beats per second, Three days, Automatic chronoGRAPH
  • New 9SC5 calibre built upon Grand Seiko’s 9SA5 calibre

Grand Seiko Tentagraph SLGC001

At last year’s Watches & Wonders, the Grand Seiko “Kodo” SLGT003 Constant Force Tourbillon was irrefutably among the top, if not the top, talking piece of the whole fair. This, while a great problem to have, creates high expectations for Grand Seiko to continue to really bring the heat each Watches & Wonders.

Undoubtedly an incredible watch, the only issue with the “Kodo” is that it was a highly limited piece for the manufacture. And, even if it were to have been a regular production model, it is understandably cost-prohibitive for most collectors to realistically enjoy in their collections.

Their marquee novelty this year, however, is a very exciting first for the brand – one that is a regular production model and much more cost-approachable than the “Kodo”. The new Grand Seiko Tentagraph SLGC001 marks the first ever fully mechanical chronograph from Grand Seiko designed by Akira Yoshida, and, again, is a regular production model within the Evolution 9 collection.

tentagraph ten beats per second three days automatic chronograph

As expected from Grand Seiko, the Tentagraph name is very intentional and precise: TEN beats per second, Three days, Automatic chronoGRAPH.

The calibre, dubbed the 9SC5, is built upon their game changing latest-gen hi-beat calibre 9SA5 which notably boasts 80 hours of power reserve, a Grand Seiko overcoil hairspring, and a dual-impulse escapement. When adapting the 9SA5 into a chronograph calibre, Grand Seiko had to ensure the movement, with the added complication, would still adhere to the Grand Seiko standard – a component of which is a minimum three days of power reserve. Due to the energy efficiency of the calibre, the 9SC5 has eight hours less power reserve than the 9SA5 – which totals exactly 72 hours down from 80.

Looking at the 9SC5 calibre, you would be forgiven for thinking it was the 9SA5 as the front of the calibre is effectively identical in aesthetic with its full balance bridge and diamond-cut bridges inspired by the river Shizukuishi. That being said, there are of course new components and architectures entering the mix.

The 9SC5 is a hi-beat automatic vertical-clutch column wheel chronograph movement, which means the pusher actuation will be butter-crisp, the chronograph seconds hand will have no stutter upon its start, and can be run continuously with minimal wear to the movement. Furthermore, Grand Seiko pledges its 72 hour power reserve is inclusive of the chronograph continuously running and the calibre, in accordance with the Grand Seiko standard, is regulated in six positions at three temperatures and assessed over 17 days to run within +5/-3 seconds per day.

Grand Seiko Tentagraph SLGC001

Of course, while the movement is a fascinating development, the case it is situated within is equally important to the offering. For this first Tentagraph entry, the Grand Seiko SLGC001 is cased in the manufacture’s high-intensity titanium and in the highly faceted Evolution 9 case design. It certainly skews on the larger side, with a diameter of 43.2mm and a case thickness of 15.3mm. But, while I do not have an exact measurement right now, I feel confident in inferring that the lug-to-lug span is close to 50mm and, at least initially, it appears to be very wearable for its size. For example, the Evolution 9 diver SLGA015 is 43.8mm in diameter and 51.5mm lug-to-lug across the wrist. So, it is fair to assume the SLGC001 lug-to-lug measurement does not span beyond that.

Grand Seiko Tentagraph SLGC001

Underneath the boxed and AR-coated sapphire crystal, and framed within the black ceramic tachymeter bezel, the blue dial primarily features Grand Seiko’s signature Mt. Iwate pattern and texture with the exception of the three recessed and concentrically textured chronograph counters and the dial-matching white on blue date disc placed at the contentious 4:30 position. At 3′ you have a running seconds counter, at 6′ a 12-hour elapsed-hours counter, and at 9′ a 30-minute elapsed-minutes counter.

Grand Seiko, as expected for an Evolution 9 design has utilized the broader and partially lumed hours and minutes handset. The faceted diamond-cut applied hour indices also feature luminous channels, and the central running chronograph seconds hand has a long portion with a luminous coating as well. The small hands of the counters, however, do not leverage luminous coatings, so they will not be the most visible in darker-lit conditions.

Grand Seiko Tentagraph SLGC001

Also in expected Evolution 9 form, the Grand Seiko Tentagraph SLGC001 makes use of a broad-widthed high-intensity titanium bracelet with the five-piece link set fully hairline brushed on their top facet – with strictly the outer shoulders of the outer link pieces thinly mirror-bevelled. It is secured to the wrist via the familiar three-fold clasp with safety buttons as well.

My initial thoughts are that this is a very neat expansion of the Evolution 9 collection, their roster of in-house mechanical calibres, and their repertoire of complications. While I doubt there are plans, at least for the moment, I would be interested to see if, like the 9SA5, the 33mm diameter and 8mm thick 9SC5 calibre ever makes its way into case geometries outside of Evolution 9 – perhaps in a dressier and more vintage-inspired package. Again, I highly doubt it at this time. But for Grand Seiko enthusiasts who like their sportier designs, this is a strong offering that surely many GS collectors will race to place an order for.

Grand Seiko Tentagraph SLGC001 pricing and availability:

Grand Seiko Tentagraph SLGC001

The Grand Seiko Tentagraph SLGC001 will be available for purchase via Grand Seiko boutiques and authorised dealers. Price: A$20,500 / US$13,700

Brand Grand Seiko
Model SLGC001 ‘Tentagraph’
Case Dimensions 43.2mm (D) x 15.3mm (T)
Case Material High-intensity titanium
Water Resistance 100m (screw-down crown)
Dial Blue Mt. Iwate dial
Crystal Sapphire crystal and caseback
Bracelet/Strap High-intensity titanium bracelet, three-fold clasp with push button release
Movement In-house automatic hi-beat 9SC5
Power Reserve 72 hours
Functions Hours, minutes, running seconds, chronograph, date
Availability Now
Price A$20,500 / US$13,700