Imagen: Grand Seiko, web oficial
The storyWhy this reference matters
Grand Seiko already had chronographs, but every one of them was Spring Drive: the 9R86 and 9R96 calibres, mechanical movements with an electromagnetic brake governed by a quartz. An entirely mechanical chronograph, without a single electronic part inside, didn't exist in the house until June 2023. It was the most visible hole in a catalogue that prides itself on making everything under its own roof, and the Tentagraph filled it without hedging.
The name is an acronym, not a Japanese word: TEN for the ten beats a second, Three days for the reserve, Automatic for the winding and GRAPH for the chronograph. The calibre 9SC5 starts from the 9SA5, so it inherits the Dual Impulse escapement and the free-sprung balance, and adds a column wheel, a vertical clutch and a three-pointed hammer that snaps all three hands back to zero in one go. Sixty jewels in total.
The vertical clutch creates no friction while the chronograph runs, and that is what makes the strong claim possible: 72 hours of reserve measured with the chronograph running continuously, not merely with it stopped. Outside, high-intensity titanium with a fixed black ceramic bezel and a tachymeter engraved in white. The blue dial recreates the texture of Mount Iwate, the mountain you can see from the Shizukuishi workshop where the watch is assembled.
SpecificationsThe numbers, in one table
| Brand | Grand Seiko |
|---|---|
| Family | Evolution 9 |
| Reference | SLGC001 |
| Years made | desde 2023 |
| Calibre | Grand Seiko 9SC5 |
| Movement | Automático |
| Frequency | 36.000 alternancias por hora (10 Hz) |
| Power reserve | Aprox. 72 horas |
| Jewels | 60 |
| Complications | Cronógrafo de 30 minutos y 12 horas · Taquímetro · Segundero pequeño |
| Diameter | 43.2 mm |
| Thickness | 15.3 mm |
| Lug to lug | 51.5 mm |
| Lug width | 23 mm |
| Case | Titanio de alta intensidad con bisel de cerámica negra |
| Crystal | Zafiro abombado tipo caja con tratamiento antirreflejos |
| Water resistance | 100 m (10 bar) |
IdentificationHow to tell it apart
43.2 mm across, 51.5 lug to lug and 15.3 thick, with 23 mm lugs — a measurement that all but forces you to keep the original bracelet. It weighs 154 grams: for the size, that's very little, and that's the point of the titanium.
There's no date. Not a window anywhere. Just three registers — thirty minutes, twelve hours and running seconds — on a blue dial in relief. That's unusual on a chronograph at this level, and it's the fastest check that you're looking at a Tentagraph.
Against the brand's Spring Drive chronographs, the difference shows in two seconds: here the small seconds hand advances in tenth-of-a-second steps, whereas on a Spring Drive it glides without steps. The case back is screwed sapphire and shows the 9SC5 with its column wheel.
CollectingWhat collectors check
Pushers and reset: run the chronograph several times. With a column wheel the feel should be clean and free of dead travel, and on reset all three hands must drop exactly to zero, not a hair short. If one stops past the mark, it needs adjusting.
Titanium scratches more easily than steel, and Zaratsu polish on titanium cannot be recovered outside the factory. The ceramic bezel won't scratch, but it chips: run a fingernail along the edge and look at the borders against the light before deciding anything.
It sells through Grand Seiko boutiques and selected dealers, so second hand it comes down to condition and a complete package. Check that the reserve really holds 72 hours with the chronograph running: that's the calibre's specific promise, and you can verify it at home with no tool but patience.
Common questionsWhat people ask us about this reference
What does Tentagraph mean?
It's an acronym: TEN for the ten beats a second, Three days for the 72-hour reserve, Automatic for the automatic winding and GRAPH for the chronograph.
Is it Grand Seiko's first chronograph?
The first fully mechanical one, yes. The brand already had chronographs, but on Spring Drive calibres (the 9R86 and 9R96), which carry a quartz regulator inside.
Does the SLGC001 have a date?
No. The dial shows only the time and the three chronograph registers: thirty minutes, twelve hours and running seconds.
How much does the Tentagraph weigh?
A hundred and fifty-four grams, thanks to the high-intensity titanium. For 43.2 mm across and 15.3 thick, that's a surprisingly low figure.
Keep readingWhere to go from here
Close relativesThe ones it gets confused with
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