Grand Seiko Ushio debuts as a compact 40.8mm Spring Drive diver that pairs a new 9RB1 movement with 300 meters of water resistance and 72 hours of power, Grand Seiko said.
The new Grand Seiko Ushio follows the brand’s Evolution 9 design language while translating tidal and coastal patterns into dial texture, according to Grand Seiko. The blue model uses a layered deep to shallow color shading to evoke light penetrating deep water, while the green model draws on nearshore shallows for a softer, calmer palette.
The dials include Grand Seiko’s signature textured finish, with clear, faceted hands and markers that preserve legibility in varied light. The rectangular marker pockets hold extra Lumibrite luminous material to improve night time legibility, Grand Seiko said.
Design and materials
The bezel uses a 120 click mechanism to support precise timing and incorporates ceramic inserts for scratch resistance and corrosion protection. Faceted marker edges and sides add polished highlights that balance the watch’s functional needs with the Evolution 9 aesthetic.
The case measures 40.8 millimeters in diameter, about 1.61 inches, a narrower footprint than many modern dive watches yet with broad lugs to keep wrist presence. Grand Seiko builds the case and bracelet from high strength titanium, which is roughly 30 percent lighter than stainless steel while retaining a metallic sheen for long term wear comfort.
The Ushio bracelet receives a redesigned extension clasp that supports three step micro adjustments across 6 millimeters and an additional 18 millimeters of extension for a total 24 millimeters of adjustment, Grand Seiko said. The clasp locks to reduce accidental opening and prioritizes practical fit adjustments for different conditions.
Water resistance and durability
The Grand Seiko Ushio is rated to 300 meters and meets a 4,800 ampere per meter magnetic resistance standard, supporting both everyday exposure and underwater use. The crystal is sapphire with an anti reflective coating and the watch uses a screw down crown and case back to strengthen overall durability, Grand Seiko said.
Movement and accuracy
The headline technical feature is the new Spring Drive U.F.A. 9RB1 movement, which delivers 72 hours of power and an annual accuracy of plus or minus 20 seconds, equal to roughly plus or minus 3 seconds per month, Grand Seiko said. The movement pairs a matured quartz oscillator with an IC chip sealed in a vacuum to reduce the effects of temperature, humidity, and light.
Each oscillator is tested across multiple temperatures and the resulting compensation data is written into the system to stabilize performance. The 9RB1 movement also includes a service friendly regulation switch and relocates the power reserve indicator to the case side for a cleaner dial, Grand Seiko said. The movement thickness is controlled to 4.7 millimeters to preserve balanced case proportions.
Both models, SLGB023 in blue and SLGB025 in green, use a 33 jewels movement architecture to balance durability and stable operation. Grand Seiko positioned the Ushio to favor functional wearability for professionals and collectors who value precision and practical detail.
Price and availability
Grand Seiko lists the SLGB023 and SLGB025 at about HK$87,800, which is approximately $11,200 (before tax), Grand Seiko said. Availability will depend on regional allocations and authorized Grand Seiko retailers, the brand added.
For collectors tracking new releases, the Grand Seiko Ushio blends Evolution 9 styling with a scaled case size and the brand’s latest Spring Drive engineering, representing a new take on a titanium professional dive watch.
