By Kien Lee

It was in when Grand Seiko presented the Kodo Constant-force Tourbillon, the Japanese manufacture's first mechanical complication. The timepiece which went on to win the Chronometry Prize at the 2022  Grand Prix d’Horlogerie de Genève. was a revolutionary watch that combined a tourbillon and a constant-force mechanism as one unit on a single axis for the first time in horological history.

In 2024 at Watches & Wonders held in Geneva, Grand Seiko unveils a new limited-edition timepiece inspired by daybreak. The design is an ephemeral opposite of its predecessor.  While the first Kodo expressed evening twilight through the delicate interplay of light and shadow that is central to Grand Seiko aesthetics, the new timepiece uses light and shadow to evoke daybreak.

The movement components have a silver tone, giving the new Kodo a subtle but bright appearance that accentuates the intricately constructed and layered parts.

For the first time in a Grand Seiko watch movement, blue sapphires are used for the jewels, adding an unexpected detail that is in perfect harmony with the design. Platinum 950 forms the watch’s inner case, while Brilliant Hard Titanium, an alloy twice as hard as stainless steel, forms the outer case, making the exterior highly resistant to scratches. Some of the case parts in both metals are Zaratsu polished to a distortion-free mirror finish, while others have a hairline finish.

The watch is powered by the uniquely innovative Caliber 9ST1, in which a constant-force mechanism and a tourbillon are set as one unit on a single axis. Because there are no wheels or other components between the two mechanisms, there is no loss or change in the torque transmitted from the constant-force mechanism to the balance wheel, which leads to a duration of approximately 50 hours for the constant-force mechanism and a highly stable amplitude for the balance. Together, these characteristics contribute to the movement’s high level of stable accuracy.

The movement consists of approximately 340 components, but more than 100 of these are packed into the “heart” of the movement, the integrated constant-force carriage and the tourbillon carriage, which is just about 10mm in diameter.

On the constant-force carriage, a single red ruby is placed on one of the arms indicating the seconds as they pass.

The inner tourbillon carriage rotates while the balance steadily vibrates at eight beats per second, and the outer constant-force carriage follows its rotation in exact one-second intervals.

The sounds of the escapement and the once-per-second impulse of the constant-force mechanism harmonize with this visual rhythm to create, for eye and ear, a deeply satisfying and reassuring heartbeat. There is a powerful yet gentle charm to this sound, which is set to a 16th note or semi-quaver.

The watch is offered with a leather strap created from a highly durable material that is specially treated in the same traditional way once used in samurai armor. But this time, a new white color was developed specifically for the new Kodo. The white strap is made through tanning with natural materials and then carefully hand-coated with layers of white urushi lacquer to create a deep sheen and a unique texture. A crocodile strap in charcoal grey also comes with the watch.