Grand Seiko has expanded its high-end lineup with the Spring Drive U.F.A. Ushio 300 Diver and the Evolution 9 Night Lake editions, pairing its smallest diver’s watch design yet with a newly refined movement rated for an annual accuracy of plus or minus 20 seconds.
When consultancy Deloitte surveyed 6,500 people across 13 countries about watch selection, only one-third reported using a traditional timepiece to check the hour, and accuracy did not rank among the top five criteria according to industry data.
Yet exact timekeeping remains a defining benchmark for Japan’s premier luxury makers.
Grand Seiko Unveils Evolution 9 Spring Drive U.F.A. Caliber Evolution and Pricing
The quest for extreme precision stretches back to 1969, when Grand Seiko introduced its Very Fine Adjusted models guaranteed to within one minute per month. That standard evolved at the turn of the millennium with the advent of Spring Drive, a mechanism blending mechanical mainspring power with quartz regulation as detailed in watchmaking reports. The technology harnesses electrical energy from an unwinding mainspring to power a quartz crystal, which sends reference signals to a glide wheel without needing a battery.
The newly designated U.F.A. line—standing for Ultra Fine Accuracy
—pushes annual variance down to plus or minus 20 seconds as reported by specialized horology coverage. Achieving this level of stability requires vacuum-sealing the integrated circuitry and quartz oscillator after a three-month aging process that shields the components from light, humidity, static, and temperature fluctuations. The manufacturer also streamlined the gear train, replacing a two-barrel setup with a single spring barrel to increase torque.
| Model and Edition | Case Diameter | MSRP (2026) / Europe Price |
|---|---|---|
| Grand Seiko Evolution 9 Spring Drive U.F.A. SLGB007 | 40mm | various pricing |
| Grand Seiko Evolution 9 Spring Drive U.F.A. Standard Models | 40mm | various pricing |
| Grand Seiko Spring Drive U.F.A. Ushio 300 Diver (SLGB023, SLGB025) | 40.8mm | €12,500 |
Spring Drive U.F.A. Ushio 300 Diver Specifications
Hand-assembled by craftsmen and women at the Shinshu Watch Studio inside a Seiko Epson facility in Shiojiri, Nagano Prefecture the Ushio 300 Diver models introduce compact proportions to the brand’s professional dive watch catalog. The High-Intensity Titanium case measures 40.8mm in diameter with a thickness of 12.9mm, making it the smallest diver in the lineup according to product specifications.
The watches utilize Caliber 9RB1, a self-winding movement featuring 33 jewels and a 72-hour power reserve. The design incorporates a 120-click ceramic bezel insert, broad faceted indexes treated with Lumibrite, and a repositioned power-reserve indicator on the dial side specifying design layouts. Water resistance reaches 300 meters, paired with a magnetic resistance rating of 4,800 A/m.
Ushio and Night Lake Dial Designs Inspired by Japanese Waters
Aesthetic choices for the new releases draw directly from natural Japanese settings. The Ushio models—available in references SLGB023 and SLGB025—feature blue and green gradient dials designed to evoke coastal waters noted by industry analysts. The blue colorway mirrors deep sea light, while the green variant reflects shallow coastal areas.
Meanwhile, the Evolution 9 Night Lake edition features a black-to-brown graded dial inspired by Lake Suwa in the Kiso mountains, crafted to capture the surface of the water as it shimmers beneath the moonlight
in the words of the manufacturer’s design brief.
Titanium Bracelets Feature Adjustable Locking Clasps
Wearability improvements extend to the bracelets and closures. The Ushio 300 Diver features a locking extension clasp with micro-adjustment capabilities documented in technical breakdowns. The mechanism provides a three-step fine-tuning adjustment of up to 6mm alongside an 18mm diving suit extension, offering a total adjustment range of 24mm.
The GS emblem on the clasp double-functions as a locking mechanism to prevent accidental release. High-Intensity Titanium is used for both the case and bracelet across the diver models, balancing lightweight comfort on the wrist with enhanced scratch and corrosion resistance.
How will the market receive the €12,500 price point for the Ushio 300 Diver?