For years, fans of Grand Seiko have wanted a smaller diver’s watch. Today, at Watches & Wonders Geneva, this popular request is answered in the form of the new 40.8mm Spring Drive U.F.A. Ushio 300 Diver, which joins the Evolution 9 Collection.
Available in two colour variations – SLGB023 (Ushio Blue) and SLGB025 (Ushio Green) – Grand Seiko’s new diver’s watch is not only its smallest but also its most accurate to be powered by Spring Drive. Every bit a robust tool watch, with a High-Intensity Titanium case providing 300 meters of water resistance, it was made possible thanks to recent updates in Spring Drive technology.
Last year at Watches & Wonders Geneva, Grand Seiko introduced the Calibre 9RB2, a Spring Drive movement boasting dramatically enhanced precision. With an accuracy of ± 20 seconds per year, the U.F.A. movement became the most accurate wristwatch movement powered by a mainspring according to Grand Seiko’s research. The Ushio 300 Diver is powered by the second movement to receive the U.F.A. designation, the new Calibre 9RB1.
While the Spring Drive Calibre 9RB1 retains the key features that defined the first U.F.A. movement, chiefly its annual accuracy rating and three days of power reserve, upgrades make it better suited for use in a diver’s watch. The power reserve indicator, formerly on the back, has been repositioned to the dial side for use when diving, and the oscillating weight has been redesigned for robustness. The at-a-glance legibility of the design is enhanced through the absence of a date window.
Like Calibre 9RB2, the new movement’s accuracy is achieved by vacuum-sealing the crystal oscillator, stabilised through a 90-day aging process, together with the IC to minimise the influence of external factors such as temperature, humidity, 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. A regulation switch can be used during after-sales service to correct any small divergences in accuracy that may occur over long periods of use. Accurate, convenient, and built for performance, Calibre 9RB2 winds quickly and efficiently thanks to the Offset Magic Lever, adapted for winding a single barrel.
The Ushio 300 Diver’s compact dimensions are made possible by the compact size of the U.F.A. movement. Its High-Intensity Titanium case measures a mere 40.8mm in diameter and 12.9mm in height. Thanks to the resilient yet lightweight metal used for both the case and bracelet, along with the highly ergonomic Evolution 9 design, it wears with remarkable comfort.
As its name implies, the Ushio 300 Diver features the return of the popular Ushio dial pattern (the term ushio means “tide” in Japanese) first seen in the SLGA015 in 2022. Inspired by the seas that surround the Japanese archipelago, the two new Ushio dials optimise legibility while putting the depth and beauty of the wave pattern front and centre. The blue dial reflects the vast expanse of the sea through a gradient that captures light streaming into the deep ocean, while the green dial finds inspiration in the shallow coastal waters near the shores. Both the hour and minute hands feature a striking, prominent design to enhance legibility, and the diamond-cut indexes have been updated for legibility – now with a rectangular shape to hold more Lumibrite and shine brighter in the dark. Each watch has a 120-click unidirectional bezel with a ceramic insert in a colour that complements the colour of the dial.
The watches come on a bracelet with a newly developed locking extension clasp with micro-adjustment for easy, tool-free operation. In addition to the three-step micro-adjustment that provides up to 6mm of fine tuning, there is also an extension feature that can be used with a diving suit, providing an additional 18mm of adjustment for a total range of 24mm. The GS emblem that appears on the outside of the clasp functions as a locking mechanism to prevent the accidental release of the clasp.
The Spring Drive U.F.A. Ushio 300 Diver will be available starting in June at Grand Seiko Boutiques and select retailer partners worldwide.
