The Grand Seiko Ushio 300 Diver wins the Sports Watch Prize at the 2026 Grand Prix d’Horlogerie de Genève.

On November 7, the 2026 Grand Prix d’Horlogerie de Genève awards ceremony took place at the Bâtiment des Forces Motrices in Geneva. At the ceremony, 14 timepieces received awards across their respective categories, while 5 discretionary prizes and the Grand Prix, awarded to the best overall timepiece among all nominated categories, were also presented. The Grand Seiko Ushio 300 Diver was awarded the Sports Watch Prize.

 

Grand Seiko Ushio 300 Diver

The winning watch is powered by the Spring Drive U.F.A. Caliber 9RB1. Based on the Caliber 9RB2 introduced in 2025, it delivers a 72-hour power reserve and an accuracy of ±20 seconds per year, making it the most accurate mainspring-powered wristwatch movement on the market today.* To ensure this precision, both the quartz oscillator and the IC are vacuum-sealed together, and the oscillator is stabilized through a unique aging process. Vacuum sealing minimizes the influence of external factors such as temperature, humidity, static electricity, and light, thereby enabling high accuracy. Each oscillator’s frequency is measured at multiple temperatures, and the resulting data is programmed into the low-power IC to enable precise temperature compensation. Such exceptional accuracy is especially valuable in a diver’s watch, where dependable timekeeping is essential, making Caliber 9RB1 ideally suited for underwater exploration.

*As of November 2026, based on Grand Seiko’s research.

 

The watch features a 40.8mm case and superb wearability. Both the case and bracelet are crafted from High-Intensity Titanium, a material approximately 30% lighter than stainless steel and distinguished by its bright, lustrous tone. The 120-click bezel enables precise adjustment, while the ceramic insert provides excellent resistance to scratches and corrosion.

In accepting the award, Seiko Watch Corporation President Akio Naito said: “This watch embodies Grand Seiko’s uncompromising pursuit of excellence, combining the robust functionality of a true diver’s watch with an exceptionally accurate movement that achieves an annual rate of ±20 seconds. We are deeply honored that this creation has been recognized at the watch industry’s most prestigious awards ceremony.”

For details of the prize-winning watch, visit: https://www.grand-seiko.com/gr-en/news/2026/pr/20260414-1
Full details of the awards are available at: http://www.gphg.org/horlogerie/en