The “Tentagraph” – the first fully mechanical chronograph from Grand Seiko

With the release of the White Birch in 2021, Grand Seiko set a new design language in stone for their latest models. Evolution 9 would see a widening of hands and hour markers, as well as a new case design that brings Grand Seiko firmly into the 21st Century. In 2023, this also marked a new evolution for the brand, with its first fully mechanical chronograph in the Grand Seiko collection – the Tentagraph. (Previous to this release of course, there was the Grand Seiko GMT Chronograph but those are driven by the hybrid-mechanical Spring Drive calibres.)

The new Tentagraph carries over the Evolution 9 design of its case and bracelet, this time, crafted from Seiko’s High Intensity Titanium measuring in at 43.2mm – appropriately sized for a sports watch. The case material also ensures that the watch is 30% lighter than its equivalent in stainless steel, and is also more resistant to scratches in comparison as well. The watch also features a ceramic bezel with a tachymeter scale engraving – a material that also protects from scratches due to its hardness. 

Typical of an Evolution 9 series Grand Seiko, the hands and markers are very much bolder in comparison to its older family members, with an enlarged 12 o’clock marker, grooved hour markers and thicker hands designed to enhance legibility. Furthermore, the markers and hands are filled with Lumibrite, Seiko’s proprietary luminescent material that ensures low-light visibility for longer periods. Its blue dial bears the famous Mount Iwate pattern, a constant source of inspiration for Grand Seiko’s watch designers that made its debut onto the watch in 2006.

The chronograph hand extends from the centre of the dial, all the way to the chapter ring where the seconds indicators are, and is bent towards the dial, maximising legibility through minimising the parallax effect when viewed at an angle. The same is done with the minute hand, to aid with legibility. The dial is also populated with chronograph subdials at 9 and 6 o’clock (minutes and hours totalisers respectively), as well as a running seconds subdial at 3 o’clock. Finishing off the watch, is a date complication at 4:30.

Housed within the watch is the Calibre 9SC5 – a movement that utilises the 9SA5 movement as a base, building a chronograph on top of the original movement, and brings its mechanical improvements to the Tentagraph. Incorporated within the movement is the Grand Seiko Dual Impluse Escapement, a system that combines the indirect energy impulses from the pallet fork with direct energy impulses from the escape wheel to the balance wheel. This results in a more energy-efficient running of the movement, and enables a power reserve of 72 hours. The watch also beats at 10Hz, a signature running frequency of Grand Seiko, having been one of the pioneers of high-beat movements since the 1960s, and also providing the basis of the name of the watch.

As with all Grand Seiko watches, the standards for timekeeping are tighter in comparison much of the industry – all watches must keep time to within -3/+5 seconds per day (a maximum variation of 8 seconds per day, in contrast to the COSC, which has a maximum variation of 10 seconds), and the Tentagraph undergoes a further 3 day gauntlet to test the watch whilst the chronograph is running.

To have a watch pass these tests with the chronograph running is a testament to the movement design of the Tentagraph, as the additional load that the chronograph mechanism places on the running of a movement can easily slow down a watch. 

On the wrist, the Tentagraph has a bold presence no doubt because of its size. At a case diameter of 43.2mm and a thickness of 15.3mm this is a big watch. However, given its titanium construction, it is not overbearing and is certainly a good candidate for a daily wearer.

That being said, with the trend these days moving towards smaller case sizes, I do think that it will be possible to iterate on this watch further down the line. A watch with this movement in stainless steel at a 40/41mm size will certainly be more appealing overall and perhaps take a big bite out of competitors with similar specifications on the market.

Available at selected Grand Seiko retailers and boutiques starting from June 2023, the Tentagraph symbolises the growth of the Grand Seiko brand since its worldwide debut a number of years back. The combination of rigorous testing to the Grand Seiko standard, movement design and the appearance of the watch itself is testament to a brand that stays one step ahead of the rest. The Tentagraph will undoubtedly make a splash amongst watch lovers, not only for its looks, but also because it represents everything that modern Grand Seiko stands for.

Technical Specifications

Grand Seiko Evolution 9 Collection- Tentagraph: SLGC001

Movement: Caliber 9SC5
Winding system: Automatic
Frequency: 36,000 vibrations per hour (10 beats per second)
Accuracy (mean daily rate): +5 to -3 seconds per day
Power reserve: 72 hours
Functions: Chronograph with 30-minute counter at 9 o’clock and 12-hour counter
at 6 o’clock
Number of jewels: 60
Diameter: 33.0mm, Thickness: 8.0mm

High-intensity titanium case and bracelet
Box-shaped sapphire crystal with anti-reflective coating
See-through screw case back. Screw-down crown.
Water resistance: 10 bar
Magnetic resistance: 4,800 A/m
Diameter: 43.2mm, Thickness: 15.3mm
Bracelet: Three-fold clasp with push button release
Recommended retail price in Europe: €14,300