Masterpiece Collection Kodo Constant-force Tourbillon SLGT005

The Kodo Constant-force Tourbillon is reborn with a new theme expressing daybreak

NEW Limited edition of 20 pcs

Grand Seiko Kodo Constant-force Tourbillon


Masterpiece Collection

USD 365,000.00

Dec.2024 Release

  • Available at the Grand Seiko Boutiques


In 2022, Grand Seiko presented its first mechanical complication, the Kodo Constant-force Tourbillon, 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. As such, it represented a major milestone in the history of Grand Seiko and was recognized by the international watch community when it was awarded the Chronometry Prize at that year’s Grand Prix d’Horlogerie de Genève.

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 delicate time when morning light begins to reclaim the sky is emphasized throughout the design, completing a portrayal of light and shadow that began two years ago. The movement components have a silver tone, giving the new Kodo a subtle but bright appearance that accentuates the intricately constructed and layered parts. The beauty of the painstakingly hand-polished components is even more pronounced in the new timepiece. For the first time in a Grand Seiko watch, blue sapphires take the place of some of the rubies, adding an unexpected detail that is in perfect harmony with the design. Carefully examined and selected, the pale blue sapphires recall a beautiful dawn.

A subtle gradation of light is expressed through the use of different materials and various types of finishing. 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. The combination of the two materials creates a natural gradation and a long-lasting beauty. 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 and women to ensure that an elegant visual harmony is revealed from every angle.

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.


Exterior: Brilliant Hard Titanium and Platinum, Caseback: Platinum and sapphire crystal
Case back: See-through case back
Case back with 6 screws
Glass Material: Box shaped sapphire crystal
Glass Coating: Anti-reflective coating on inner surface
Case size: Diameter 43.8mm Lug-to-lug 50.6mm Thickness 12.9mm
Band width: 22mm
Band Material: Calfskin
Clasp type: Three-fold clasp with push button release
Caliber no.: 9ST1 Instructions
Movement Type: Manual winding
Power reserve: Approx. 72 hours(3 days)(Constant-force: 50 Hours)
Mean daily rate: +5 to -3 seconds per day
  • Mean daily rate is a mean value of daily rates in a condition where the movement before assembly in a case is measured in six positions in a fixed manner under artificially controlled environment for 12 days.
Normal usage accuracy: +5 to -1 seconds per day
Water resistance: 10 bar
Magnetic resistance: 4,800 A/m
Other details / Features:
  • LIMITED EDITION on the case back
  • Serial number engraved on the case back
  • Platinum buckle (PT950)
  • 28,800 vibrations per hour (8 beats per second)
  • Power reserve indicator

The integration of two mechanisms

Caliber 9ST1 is complex in its engineering and design but is based on the simple insight that the integration of a constant-force mechanism and a tourbillon as one unit on a single axis would deliver practical benefits. 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. This leads to an increased duration of 50 hours for the constant-force mechanism and a more stable amplitude of the balance. Together, these characteristics deliver the very stable accuracy of the movement.

Innovation in precision, beauty, and sound

The integration of the two mechanisms creates a dazzling visual effect. The inner tourbillon carriage rotates 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 sounds of the escapement and the once-per-second impulse of the constant-force mechanism harmonize with this regular visual rhythm to create, for both the eye and the ear, a deeply satisfying and reassuring heartbeat.

Two materials in perfect harmony

The case is constructed from both Platinum 950 and Grand Seiko’s Brilliant Hard Titanium to achieve a long-lasting beauty. Some of the case parts in both materials are mirror polished and others have a hairline finish; both processes are completed by hand by highly skilled craftsmen and women to ensure that, from every angle, a visually pleasing harmony is revealed. The two case materials combine 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.

Light, shadow, and space

Thanks to the integration of the two key mechanisms, Caliber 9ST1 has room to breathe within the case and there is sufficient space for light to penetrate, through both the front and back of the case, revealing the beauty of the hand finishing. For the same reason, the delicate interplay of light and shadow that is central to the Grand Seiko aesthetic is there to be enjoyed in the subtle shade gradations, angles, and textures. Each major component is painstakingly finished by hand using a variety of techniques to endow the movement with the quiet yet enduring sparkle that is the hallmark of Grand Seiko.