The Evolution of Light and Shade: Grand Seiko Unveils Latest Kodo Constant-force Tourbillon

With the Kodo Constant-force Tourbillon, Grand Seiko demonstrated its outstanding technical expertise at Watches and Wonders 2022. With a charming understatement, the Japanese luxury watch brand called this mechanical masterpiece its “first mechanical complication.” Well, its two sophisticated mechanisms, originally designed to improve the accuracy of timekeeping, combined in a single unit on a single axis for the first time in history, took the watch world by storm and was awarded the Chronometry Prize at that year’s Grand Prix d’Horlogerie de Genève.

The key to its high accuracy is the design of the two mechanisms on one axis. Since there are no wheels or other components between them, there is no loss or change in the torque transmitted from the constant-force mechanism to the balance wheel, resulting in a highly stable amplitude of the balance. While the leitmotif of the first Kodo was the twilight in the evening hours, expressed through the interplay of light and shadow that is central to Grand Seiko’s aesthetic, the new SLGT005G, introduced at this year’s Watches and Wonders, uses these elements to evoke daybreak.

The delicate moment when the morning light begins to reclaim the sky inspired Grand Seiko to create the new edition of the Kodo. This aura is emphasized throughout the open design, completing a portrayal of light and shadow. The movement components, meticulously hand-polished, have a silver tone, giving the new Kodo a subtle but bright appearance that accentuates the intricately constructed and layered parts of the hand-wound Caliber 9ST1 with a power reserve of 50 hours. There is sufficient space for light to penetrate, through both the front and back of the case, revealing the beauty of mechanics. 

Each major component is painstakingly finished by hand using a variety of techniques to endow the movement with the shimmer that is the hallmark of Grand Seiko. Notably, Grand Seiko has replaced some of the rubies with blue sapphires, adding an unexpected detail that blends in perfectly with the design.

The combination of the two mechanisms not only results in higher precision in the Kodo Constant-Force Tourbillon, but is a sight to behold. The inner tourbillon cage rotates smoothly while the balance oscillates constantly at eight beats per second, and the outer constant-force cage follows this rotational motion at precise one-second intervals. This sequence, which can also be followed by ear, led Grand Seiko to name this bravura piece “Kodo,” which translates to “heartbeat.”

To further emphasize the theme of dawn, a subtle gradation of light is expressed through the use of different materials and finishes. Platinum 950 forms the inner case of the watch, while Grand Seiko’s 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. Each process is completed by hand by highly skilled craftsmen to ensure that an elegant visual harmony is revealed from every angle.

Like its predecessor, the SLGT005G comes with a strap that incorporates an ancient treatment of samurai armor: the white strap is made by tanning with natural materials and then carefully hand-applied with layers of white urushi lacquer to create a deep shine and unique texture. A charcoal gray crocodile leather strap is also included.

Limited to 20 pieces, the Grand Seiko Kodo Constant-force Tourbillon has a sticker price of $365,000.

To learn more, visit Grand Seiko, here.

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