In 2020, Grand Seiko raised eyebrows and the occasional heart rate with their announcement of the T0 Constant-force Tourbillon, a complicated concept that is now a reality. Comprising 340 components, caliber 9ST1 is a mechanical achievement that sees the constant force mechanism integrated into the tourbillon cage, an ingenious solution that delivers numerous benefits.

Fundamentally a constant force mechanism exists to ensure and even amount of torque is delivered throughout the power reserve of the watch. In a world-first, Grand Seiko has developed a remontoire-type constant force mechanism, to ensure even power supply, and paired it with a tourbillon, to minimise errors that arise due to the watches position. That the remontoire is a deadbeat mechanism is remarkable, not least because it results in a ‘ticking’ tourbillon.  The remontoire exists as an outer cage around the tourbillon itself. It is driven by the gear train and, in turn, provides energy to the inner tourbillon cage. The genius of Kodo is that both these sympathetic complications exist on the same axis, allowing for greater energy efficiency. Because they are on the same axis, there’s no loss of torque between the two, allowing for 50 hours’ duration for the constant force mechanism (with 72 hours of power reserve), and stable amplitude of the balance resulting in greater accuracy — something proved during the 34-day testing process the caliber goes through.

Technique is only part of the picture, though. Grand Seiko is famous for their particular aesthetic and style, and this new mechanism fits the bill. Though the open-worked design is a look we don’t associate with the brand, the design of the movement had to be wearable, and indeed it is. The reference SLGT003 is housed in a platinum and Brilliant Hard Titanium case rated to 100 meters. At the same time, the mechanism is finished to Grand Seiko’s famously high standards while also allowing enough air and light into the movement, highlighting the harmony and the craft. This watch will be limited to 20 pieces, with an approximate retail price of €370,000.

While the watch itself is an incredible achievement, it’s what it represents for Grand Seiko’s future that’s truly exciting. This watch is the product of a new design team and studio, the Atelier Ginza, based in the heart of Tokyo, where Kintaro Hattori founded Seiko in 1881. This metropolitan watchmaker looks set to create some of the world’s finest watches in the years to come, and we can’t wait.

Tech Specs

Kodo Constant-force Tourbillon

Movement: Manual-winding caliber 9ST1 with constant-force tourbillon; 72 hours of power reserve, 50 hours on the constant force mechanism
Functions: Hours, minutes, small seconds (on tourbillon cage), constant force mechanism
Case: 43.8mm x 12.9mm; Platinum 950 and Brilliant Hard Titanium; water-resistant to 100m
Strap: Calf strap with Platinum 950 three-fold clasp with push-button release; double-sided crocodile strap included
Availability: October 2022; limited to 20 pieces.