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SPOTLIGHT: Grand Seiko's Tentagraph has impressive specs for chronograph lovers

The Grand Seiko Tentagraph in high-intensity titanium case and bracelet.

This year, Grand Seiko has created a chronograph that heralds a new industry standard. Find out what makes the Tentagraph so outstanding.

In 1960, the finest and most experienced watchmakers in Japan were gathered together in Suwa. They were tasked with one challenge: to set a new horological standard for Japanese watchmaking that would encompass technological innovation and refined aesthetics in design and manufacturing. This was the birth of Grand Seiko. 

The Ref. 3180 is Grand Seiko's first watch from 1960.

The Ref. 3180 is Grand Seiko’s first watch from 1960.

Over the next few years, Grand Seiko introduced a set of design aesthetics as well as high-performance calibres, including the first Hi-Beat movements from Japan. Models such as the Self-Dater and the 44GS would further define the brand’s success during this period. 

Japanese Innovation

Towards the late ’90s, Grand Seiko sought to develop a new movement that would set new standards in Japanese mechanical watchmaking. The 9S aimed to exceed the COSC’s Chronometer standards and offer greater power reserve than typical movements. The brand expanded its testing requirements and invented new alloys such as SPRON, a nickel-cobalt material suitable for use in mainsprings and hairsprings, as well as manufacturing techniques to achieve its own targets.

Grand Seiko introduced the 9S51 and 9S55 calibres in 1998, the first in a series of mechanical movements demonstrating Japanese watchmaking at its finest. Not only were these movements highly resilient and accurate, but they were also finished to impressive standards. Every chamfer is hand-finished, and every surface is treated using various techniques, from perlage to vertical stripes.

Grand Seiko's 9S85 calibre is its first high-beat movement, produced in 2009.
Grand Seiko’s 9S85 calibre is its first Hi-Beat movement in over 40 years, produced in 2009.

2009 saw the introduction of the 9S85 movement, the first Hi-Beat movement from Grand Seiko in over 40 years and featuring a new SPRON alloy mainspring with higher strength and greater magnetic and shock resistance. The new mainspring offered 10 per cent more power reserve and maintained precision to +5/-3 seconds daily. But Grand Seiko’s movement engineers sought to go one step further.
 
New MEMS (Micro Electro Mechanical Systems) fabrication solutions meant Grand Seiko’s engineers could create components with nanometre precision. In addition, a new version of the SPRON alloy for the hairspring, the SPRON 610, enabled even greater performance improvements to its movements. With these, they began to consider how they could improve the three core parts of the movement: the escapement, balance spring, and gear train. 

Grand Seiko's original Dual Impulse Escapement concept, shown here.
Grand Seiko’s original Dual Impulse Escapement concept.

The first aspect of these improvements came from a new Dual Impulse Escapement using a starfish-shaped escapement wheel that transmits power to the balance directly from one direction and a traditional pallet fork in the opposite. The second was a new balance wheel design with an overcoil hairspring that’s specially curved to ensure it breathes evenly in all watch positions. 
 
Finally, the entire layout of the movement was reworked, with twin barrels in sequence, to deliver greater power reserve while slimming down the new movement. With a new horizontal layout for the entire gear train and the mainspring barrel, there’s greater efficiency in the transmission of power and a more balanced design in the movement. The design of the movement’s bridges is a homage to the Shizukuishi River, a regular source of inspiration for Grand Seiko’s timekeepers.  

The Grand Seiko 9SA5 Calibre is the brand's new high-beat movement introduced in 2020 and the basis for the Tentagraph.
The Grand Seiko 9SA5 calibre is the brand’s new Hi-Beat movement introduced in 2020 and the basis for the Tentagraph.

These numerous innovations were integrated into the new Hi-Beat Calibre 9SA5 and introduced to the world in 2020. With this new development, Grand Seiko began to embark on its latest project: its first in-house automatic chronograph watch.

The Tentagraph

Grand Seiko’s latest timepiece, the Tentagraph, is named for the defining qualities of the watch: a 10-beat movement with at least three days of power reserve, self-winding, and a chronograph. Using the Calibre 9SA5 as its base, its watchmakers designed a vertically coupled, column wheel-controlled chronograph movement that smoothly engages the timekeeping gear train when the chronograph is activated and ensures there is no jumping of the chronograph seconds hand, unlike some horizontally coupled chronographs. A three-point hammer ensures the reset is just as smooth, with the hands returning to zero simultaneously.

The Grand Seiko 9SC5 calibre features a vertically coupled chronograph based on the 9SA5 calibre.
The Grand Seiko 9SC5 calibre features a vertically coupled chronograph based on the 9SA5.

The Calibre 9SC5 incorporates all of the 9SA5’s new improvements, including the Dual Impulse Escapement, SPRON alloy springs, and redesigned balance. A vertically coupled chronograph also ensures the amplitude of the balance does not dip significantly when the chronograph is activated, meaning the watch can retain a 72-hour power reserve and maintain its accuracy above COSC standards.

The Grand Seiko Tentagraph, the watchmaker's first automatic, mechanical chronograph ever.
The Grand Seiko Tentagraph, the watchmaker’s first automatic, mechanical chronograph ever.

The 9SC5 movement is housed in Grand Seiko’s Evolution 9 design principles introduced in 2020. The dial features large, grooved indexes and sharp, strong hands that allow one to read the time precisely. These are coated in LumiBrite to ensure the watch is fully legible at night. The Tentagraph’s chronograph seconds hand curves slightly downwards to the edge of the deep blue, sunray-brushed dial, which bears Grand Seiko’s signature Mt Iwate pattern. The design looks like hand-engraved finishings similar to the ridges of the mountain smoothened by nature over time.  

A closer look at the textured dial on the Grand Seiko Tentagraph, which is inspired by the ridges of Mt Iwate at night.
A closer look at the textured dial on the Grand Seiko Tentagraph, inspired by the ridges of Mt Iwate at night.

Three counters on the dial indicate the small seconds, 12-hour, and 30-minute totalisers at 3, 6, and 9 o’clock, respectively. A small, instantaneous date window sits between the 4 and 5 o’clock markers. A minute track with 0.2-second increments is printed on the rehaut of the watch, reflecting the 5Hz movement powering this watch. 

The sunk-in counters, date window and minute track of the Grand Seiko Tentagraph reflect the tonal blue hue of the entire watch. This is the first time a date window is coloured blue on a Grand Seiko watch.
The sunk-in counters, date window, and minute track of the Grand Seiko Tentagraph reflect the tonal blue hue of the entire watch. This is the first time a date window is coloured blue in a Grand Seiko watch.

The case of the watch is gently curved to fit comfortably on your wrist, with widened lugs that have Zaratsu-polished chamfers and edges with smooth brushed surfaces. To match the sporty nature of the chronograph, the brand has also housed the Tentagraph in high-intensity titanium, which is an alloy of titanium that’s 30 per cent lighter and more scratch-resistant than steel. It also features a ceramic bezel with tachymeter markings in white. 

The Tentagraph’s case is matched with a three-link, high-intensity titanium bracelet with polished end links and a brushed middle link. The links are faceted at the corners to ensure the bracelet sits smoothly on the wrist and flexes freely

A side view of the Grand Seiko Tentagraph's high-intensity titanium case shows the sharp angles of the Evolution 9 design and how it joins the bracelet of the watch.
A side view of the Grand Seiko Tentagraph’s high-intensity titanium case shows the sharp angles of the Evolution 9 design and how it joins the watch’s bracelet.

Grand Seiko’s first automatic and fully mechanical chronograph represents a new stage in its fine watchmaking standards. To ensure the watch met its own exacting standards, the brand developed a new set of testing procedures, assessing its timekeeping in six positions at three temperature ranges over 17 days, with another three days to test the performance of the watch while the chronograph is running. Like an overachiever, the brand continues to create record-breaking timekeepers that are both beautifully crafted and technically sophisticated. With this high-performance chronograph, new opportunities are surely on the horizon for the brand.

* A longer version of this article is available on CROWN Singapore’s digital and print magazine. Subscribe here

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Editor

Darren has been writing about, and admiring the craft of watchmaking for over a dozen years. He considers himself lucky to live in a golden age of horology, and firmly believes that the most difficult watches to design are the simplest and the most intriguing to discover.


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