Grand Seiko

Based on a concept movement introduced in 2020, known then as the T0, the 43.8mm by 12.9mm platinum and titanium Kodo (price upon request) is Grand Seiko’s first constant-force tourbillon and first skeleton watch in its 62-year-long history – and is a world first as a tourbillon and constant-force mechanism operating on one axis.

Tourbillons are relatively pervasive in watchmaking, but constant-force mechanisms are difficult to manufacture and far rarer. The purpose of the system is to deliver a constant flow of energy to the escapement, regardless of whether the power reserve is high or low. Coupled with the tourbillon, which rotates the escapement to prevent errors caused by gravity, it makes for a remarkably accurate timepiece.

The combination is so difficult to achieve only a handful of watchmakers – FP Journe, IWC and Haldimann – have achieved it. Grand Seiko maximised the complications by executing the two on the same plane to increase energy efficiency, delivering 50 hours of constant force at an accuracy of +5 to -3 seconds per day.

The piece, of which only 20 will be made, represents a new very high-end and technical chapter in Grand Seiko’s history, suggesting it won’t be relying solely on its popular sports watches in the future.