Presented at Watches and Wonders 2022, the Grand Seiko Kodo Constant-force Tourbillon SLGT003 with new Calibre 9ST1 has a price of €370,000/$350,000.
Following the creation in 2020 of the T0 Constant-force Tourbillon concept movement incorporating a constant-force mechanism and a tourbillon as one unit on a single axis, Grand Seiko is now presenting the first timepiece based on that technology, the Kodo Constant-force Tourbillon which is also the most complicated wristwatch model ever produced by this brand.
This exclusive limited edition is powered by the evolution of the T0, the new Caliber 9ST1 which is smaller than its concept movement predecessor as well as stable for a longer time.
Caliber 9ST1 sets a new standard of accuracy thanks to a testing procedure during which each movement is tested for a full 48 hours in each of six positions and at three temperatures. This is twice as long as the Grand Seiko standard.
Each movement is assessed over the course of 34 days to verify its accuracy, and when the tests are completed, the performance characteristics of each movement are detailed in the individual certificate provided with every watch.
The new Kodo - the Japanese word for heartbeat - comes in a 43.8 mm x 12.9 mm round case crafted from both Platinum 950 and Grand Seiko’s Brilliant Hard Titanium. Some surfaces are mirror polished while others have a hairline finish. These operations are performed by hand by skilled specialists. The combination of the two materials is more evident at the tapered end of the lugs where a small open space between each lug adds character to the overall design.
A box shaped sapphire crystal with anti-reflective coating on the inner surface reveals the complexity of the hand-wound Caliber 9ST1.
The integration of a constant-force mechanism and a tourbillon as one unit on a single axis bypasses the need for wheels or other components between the two mechanisms with the benefit that there is no loss or change in the torque transmitted from the constant-force mechanism to the balance wheel.
The result is an increased duration of 50 hours for the constant-force mechanism (vs a power reserve of the movement of 72 hours) and a more stable amplitude of the balance.
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.
The reduction of volume is another clear benefit as designers had freedom when defining the unique aesthetics of the watch.
Secured by 6 screws, the caseback reveals more details of the mechanism together with the individual number (xx/20) and the water resistance (10 bar) of the watch.
As remarked by the inscription "SIXTEENTH NOTE FEEL" around the tourbillon, the sounds of the escapement and of the once-per-second impulse of the constant-force mechanism are set to a 16th note or semi-quaver which is made possible by 9ST1 being the movement with the highest frequency (4 Hz or 28,800 vibrations per hour) ever to incorporate a constant-force mechanism.
Grand Seiko says that the accuracy of the Kodo is +5 to -3 seconds per day when static for 48 hours. In all sincerity, we would have definitely expected a better performance considering the type of mechanisms and the price of the timepiece.
Available from October 2022, the Grand Seiko Kodo Constant-force Tourbillon ref. SLGT003 is a limited edition of 20 pieces with a price of Euro 370,000 / US$ 350,000. grand-seiko.com
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