THE HEART OF THE MATTER
The Grand Seiko Kodo Constant-force Tourbillon combines two complications in one beautiful creation
Grand Seiko’s 10-year project has culminated in the Kodo — its debut high complication combining a constant-force mechanism and a tourbillon as one unit on a single axis — a first in horological history.
Powered by the innovative Caliber 9ST1, the Kodo Constant-force Tourbillon was unveiled recently at Watches & Wonders Geneva
2022 where Grand Seiko participated for the first time in showcasing its haute horlogerie.
The open-work design and sapphire crystal case back reveals the mechanical complication in motion, complemented by a unique sound that together gives the watch its kodo — Japanese for heartbeat.
The high-complication model was designed by an elite group of Grand Seiko’s watchmakers and designers who are part of a new studio, the Atelier Ginza in Tokyo, where Kintaro Hattori started his business in 1881.
The launch of the Grand Seiko brand in 1960 reinforced Hattori’s determination to make the world’s finest watches.
The Grand Seiko Kodo was engineered to work its magic on a single axis, with the integration eliminating components between the two mechanisms. Hence there is no loss or change in the torque transmitted from the constant-force mechanism to the balance wheel.
This leads to an increased duration of 50 hours for the constant-force mechanism and a more stable amplitude of the balance that together promote the movement’s accuracy.
Thanks to the Caliber 9ST1, the Grand Seiko Kodo has set a new standard. It was tested in each of six positions and at three temperatures for a full 48 hours, which is twice as long as the industry standard. Furthermore, each movement is assessed over the course of 34 days to verify its accuracy.
The integration of the two mechanisms also allows the optimum use of space, while the movement’s reduced volume enhances the watch’s aesthetics and wearability.
Creating a mesmerising visual effect, the inner tourbillon carriage rotates smoothly as the balance steadily vibrates at eight beats per second and the outer constant-force carriage follows its rotation at exact one-second intervals.
Moreover, the sounds of the escapement and of the once-per-second impulse of the constant-force mechanism harmonise with the visual rhythm for the watch’s signature sound.
A hacking function allows stopping the rotating tourbillon carriage when the crown is pulled out to adjust the time to the precise second.
The constant-force carriage has a ruby on one of its arms which acts as a small seconds hand while the hour hand has an extra facet at its tip to enhance readability.
The sapphire crystal case back reveals the intricate construction and the movement’s finishing.
Each major component is painstakingly finished by hand using a variety of techniques that highlight Japanese craftmanship in imparting an interplay of light and shadow — a hallmark of the Grand Seiko aesthetic.
The beauty of the watch is illuminated by light penetrating through both the front and back of the case made from Platinum 950 and Grand Seiko’s Brilliant Hard Titanium.
Some case parts are Zaratsu polished and others have a hairline finish for a harmonious visual effect.
The two case materials meet most evidently at the tapered end of the lugs where a small open space between each lug adds a lightness and unique aspect to the overall design.
The Grand Seiko Kodo is matched with a calf strap treated in the same traditional way for creating high-durability material once used in samurai armour. Its surface is painted by hand with Urushi lacquer in a multi-coating process that gives the strap a delicate sheen.
The limited edition of 20 pieces will be available in October.