Spring Drive U.F.A. "Ushio" 300 Diver 40.8mm

Accuracy meets capability

The Grand Seiko Spring Drive U.F.A. Ushio 300 Diver represents a new vision for technical achievement in a newly sized 40.8mm High-Intensity Titanium case – a first for Grand Seiko's pioneering dive watch collection. Like every Grand Seiko watch, this new creation has been painstakingly engineered to strike a perfect balance between capability, wearability & aesthetic beauty, and staggering accuracy – all hallmarks of the Grand Seiko name. 

As part of this diver refresh, the prominent dial indexes of the Evolution 9 Style are meticulously crafted with multiple facets. The edges and sides of the indexes are precisely diamond-cut for exceptional brilliance, while their rectangular shape accommodates sufficient Lumibrite for superb legibility in any lighting condition. Both the hour and minute hands strike a sharply defined and powerful form, ensuring outstanding legibility at a glance. 

This reference is characterized by its textured “Ushio” dial, a design theme that has
been part of the Grand Seiko diver’s watch since 2022. The term ushio, which means “tide” in Japanese, evokes the waters that surround the Japanese archipelago, a timeless source of inspiration in Japan’s culture and art. 

Powering this watch is Grand Seiko's own 9RB1 movement, which is hand-assembled by the highly skilled craftsmen and women of the Shinshu Watch Studio, located in a Seiko Epson facility in the city of Shiojiri in Nagano Prefecture. The movement’s annual accuracy of ±20 seconds is achieved by vacuum sealing the crystal oscillator, which has been stabilized through a three-month aging process, together with the IC, minimizing the influence of external factors such as temperature, humidity, static electricity, and light. Each oscillator’s frequency is measured at multiple temperatures, and the resulting data is programmed into the low-power IC to enable precise thermo-compensation. The movement features a regulation switch that can be used during after-sales service to correct any divergences in accuracy that may occur over long periods of use.

Thanks to the movement’s compact design, the new models feature a case diameter of just 40.8mm, the smallest of any Grand Seiko diver’s watch, ensuring a comfortable fit for a wide range of wrist sizes. 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.