At Watches and Wonders Geneva 2025, Grand Seiko unveiled its new Spring Drive U.F.A. movement, which offers an impressive annual accuracy of ± 20 seconds and marks the latest evolution in its decades-long pursuit of high accuracy in watchmaking. This movement now powers a new limited-edition watch made of Ever Brilliant Steel, a stainless-steel alloy renowned for its exceptional corrosion resistance and bright hue. The new SLGB005 Ice Forest “Violet Dawn” brings together high accuracy, advanced materials, and the Evolution 9 Style, reflecting Grand Seiko’s commitment to an approach to watchmaking that champions performance and practicality for daily wear. But surely, the most salient feature of this new reference is its high accuracy.
The quest for high accuracy has been the cornerstone of Grand Seiko watchmaking from the start, beginning with the Caliber 3180, which powered the first Grand Seiko. Released in 1960, it was Japan’s first movement to meet the Swiss chronometer standard of the day. Since then, GS has consistently pursued accuracy as a primary goal. It established the Grand Seiko Standard in 1966, devising a testing regimen that was more rigorous than the chronometer standard. It created the V.F.A. (short for Very Fine Adjusted) in 1969, achieving a monthly accuracy of one minute. And it launched 9R Spring Drive in 2004 with an accuracy of ±15 seconds per month, the culmination of nearly three decades of development. Then came the Spring Drive 9RA series in 2020, with a combined monthly accuracy of ±10 seconds and five days of power reserve.
The U.F.A. Caliber 9RB2 is the most accurate mainspring-powered movement in the world as of April 2025, according to Grand Seiko’s research. With an annual accuracy of ±20 seconds, efficient automatic winding courtesy of the Offset Magic Lever, and a power reserve of 72 hours, the movement is expertly engineered for both practicality and performance. Moreover, thanks to its compact dimensions (30mm in diameter and 5.02mm thick), Caliber 9RB2 has allowed Grand Seiko to make its smallest Spring Drive watch at 37mm in diameter, ideally sized for those with smaller wrists.
Several features and innovations contribute to Caliber 9RB2’s accuracy, efficiency, and beauty. Its ±20-second annual accuracy is achieved thanks to advanced manufacturing and processing methods for the 90-day-aged quartz oscillator and a newly designed IC. Like the Caliber 9RA series before it, the frequency of each oscillator is measured at several temperatures, with the resulting data necessary for thermo-compensation programmed into the lower-power IC. The oscillator and the sensor are vacuum sealed to minimize temperature differences while protecting against external factors like humidity, static electricity, and light. It is also the first Spring Drive movement to feature a regulation switch, a feature that can be used during after-sales service to correct any small divergences in accuracy that may occur after long periods of use.
Visible through the sapphire crystal case back, the U.F.A. movement is finished in a way that pays tribute to the frost-covered trees of Shinshu, with jewels that echo the glittering stars that dot the sky on clear winter nights.
Just like the High-Intensity Titanium and Platinum 950 models that launched at Watches & Wonders, the new SLGB005 features a pressed pattern dial inspired by forests near the Shinshu Watch Studio, where the U.F.A. and other Spring Drive movements are made. To the east of this studio lie the Kirigamine Highlands, where frost-covered trees can be observed during harsh winter months. The dial of the SLGB005 captures a moment in the early morning hours when the day’s first light bathes these frost-covered trees to create a violet dawn.
The Ever-Brilliant Steel from which the case and bracelet are made boasts a PREN (Pitting Resistance Equivalent Number) over 40, which means that this exceptional material is classified as “super stainless steel.” Ever-Brilliant Steel has a brighter and more brilliant appearance compared to other stainless steels, enhancing the effect of Grand Seiko’s signature Zaratsu polishing.
The SLGB005 will be available as a limited edition of 1,300 at the Grand Seiko Boutiques and select retail partners worldwide, beginning in November 2025.
