In the 1960s, the pursuit of precision at Grand Seiko reached its apex in 1969. It was not only the year Seiko unveiled the world’s first quartz watch, the Astron, but also the year Grand Seiko introduced its most accurate mechanical watches to date: the V.F.A., or “Very Fine Adjusted” models. The V.F.A. designation represented the very pinnacle of precision at Grand Seiko, guaranteeing not only ±2 seconds per day, but also accuracy to within a minute per month for the first two years of ownership. These watches surpassed even Grand Seiko’s Special Standard and were produced in extremely limited numbers across just eleven references from 1969 to 1972. The V.F.A. program was ultimately eclipsed by the quartz revolution. By 1975, mechanical Grand Seiko watches had vanished from the catalog, overtaken by the superior accuracy and commercial appeal of quartz technology. The Grand Seiko name would not reappear until 1988, and it was not until 1998 that mechanical models returned, coinciding with the debut of Spring Drive technology at Baselworld. In 2004, Grand Seiko introduced the first Spring Drive model, powered by the Caliber 9R65, which combined automatic winding and a 72-hour power reserve with a monthly accuracy of ±15 seconds.

At Watches & Wonders this year, Grand Seiko presents the most accurate Spring Drive movement ever made, which carries the Ultra Fine Accuracy (UFA) designation. The new Caliber 9RB2 is accurate to ± 20 seconds per year. This is a figure once unthinkable for a spring-powered watch. By comparison, the 9RA5 is accurate to ± 10 seconds per month.

Introducing Spring Drive U.F.A. SLGB001 And SLGB003

The new movement is making its debut in two watches: the SLGB001 in platinum, limited to 80 pieces, and the SLGB003 in High-Intensity Titanium that is a regular production model. The latter also debuts a newly developed three-step micro-adjustment folding clasp, allowing for sizing in 2mm increments.

From left: Grand Seiko Spring Drive U.F.A. Titanium Ref. SLGB003 and Platinum Ref. SLGB001. Image: Revolution ©

Both watches are part of the Evolution 9 collection which has been steadily redefining Grand Seiko’s design language and technical standards. They are watches that are as refined in performance as they are in appearance. Notably, the new models have a case diameter of just 37mm, making them the smallest Spring Drive models to date. At 11.4mm in height, they wear slim on the wrist, yet retain the robust build quality the brand is known for. Both cases are depth rated to 100 metres. In platinum, the watch leans unmistakably into formal territory — a dress watch in both material and execution. But in High-Intensity Titanium on a bracelet, as seen on the SLGB003, it occupies a more nuanced space. It is neither an outright sports watch nor a traditional dress watch, but rather a thoughtful blend of the two, which is perfect for daily wear.

Grand Seiko Spring Drive U.F.A. Titanium Ref. SLGB003. Image: Revolution ©

Grand Seiko Spring Drive U.F.A. Platinum Ref. SLGB001. Image: Revolution ©

The lugs are slim, yet proportionally substantial for their compact case diameters, creating a balanced silhouette that provides both comfort and wrist presence. The top surfaces and flanks are satin-brushed and are delineated by a slim but pronounced polished bevel. The bezel has two distinct upper and lower bevels that are polished and brushed, and it appears wider in these models relative to their compact proportions. This added visual weight draws the eye inward, framing the dial with greater presence while simultaneously emphasising the finishing quality of the case.

The dials are inspired by the frost-covered trees of the Kirigamine Highlands, located east of the Shinshu Watch Studio. Their intricate textures and soft blue tones evoke these rugged, ice-laden landscapes in winter. On the titanium model, the dial takes on a silvery-blue hue, reminiscent of frozen forests seen through crisp mountain air. The platinum version has a slightly deeper shade of blue. As with the rest of the collection, the hands and markers are large, multifaceted and highly polished.

Spring Drive Caliber 9RB2

Spring Drive is one of the great marvels of modern watchmaking, and it bears repeating that it is an electromechanical movement developed to overcome the inherent limitations of both mechanical and quartz watches, specifically the wear-prone lever escapement in mechanical movements and the dependence on batteries and electrolytic capacitors in quartz watches. While offering superior accuracy to traditional mechanical watches, Spring Drive retains a fully mechanical gear train, powered by a conventional mainspring.

Spring Drive Caliber 9RB2 (Revolution©)

What sets it apart is the absence of a traditional escapement. Instead, it features a glide wheel, which controls the unwinding of the mainspring with the help of two tiny electromagnets. As the glide wheel spins, it generates a small amount of electrical energy that powers an integrated circuit and a quartz oscillator vibrating at 32,768 Hz. The oscillator sends a reference signal to the circuit, which contains a logic module that continuously compares this signal with the actual speed of the glide wheel. When the glide wheel spins too quickly, the circuit applies a braking force via the electromagnets to regulate its speed to exactly eight revolutions per second. Because the glide wheel turns smoothly, as opposed to a traditional lever escapement that provides the characteristic “tick tock” of a movement, the entire gear train advances in a smooth, continuous motion. This results in the Spring Drive’s signature gliding seconds hand.

The Caliber 9RB2 achieves its remarkable ±20 seconds per year precision through a combination of refinements across the regulating system. The quartz crystal is aged for three months to ensure frequency stability over the long term, which is part of Grand Seiko’s baseline for all quartz. Each individual quartz oscillator is tested across a range of temperatures to determine how its frequency shifts with thermal change after being cased, when real-world thermal behaviour is most representative. That data is programmed into a newly developed, ultra-low-power silicon-on-insulator (SOI) integrated circuit, which controls the regulation system with exceptional accuracy. A temperature sensor embedded in the IC takes readings 540 times per day, enabling the circuit to respond rapidly and precisely to even the smallest thermal variations.

The oscillating weight is engraved with the words “SPRING DRIVE ULTRA FINE ACCURACY”. Image: Revolution ©

To further stabilise the regulating environment, the quartz oscillator and sensor are housed together in a vacuum-sealed package. This eliminates internal temperature differentials and protects the regulating components from external influences such as humidity, static electricity and light, all of which can subtly impact long-term performance.

A final innovation is the inclusion of a regulation switch, the first of its kind in any Spring Drive movement. This feature, visible along the periphery of the movement near the crown, allows watchmakers to adjust the rate during servicing to correct for gradual frequency drift that may develop over time.

The Caliber 9RB2 relies on a single slim barrel which delivers a 72-hour power reserve, with a power reserve indicator located on the bridge side of the movement. It also uses a new Magic Lever with optimised geometry and is implanted away from the centre of the movement to reduce its thickness. As a result, the 9RB2 measures just 30mm by 5.02mm.

With this new development, Grand Seiko brings Spring Drive into a new realm of precision – one that echoes the ambition of the original V.F.A. watches. These watches were never produced in large numbers, but for Grand Seiko enthusiasts with a broader interest in horological progress and the pursuit of ultimate precision, the Spring Drive U.F.A. models are a powerful reminder that the ideals of the past continue to shape the present. That it arrives in a watch of such restrained proportions only deepens its appeal, offering a synthesis of high-concept engineering and everyday wearability that speaks fluently to Grand Seiko’s philosophy.

Grand Seiko Spring Drive U.F.A. Platinum Ref. SLGB001 (Revolution©)

Tech Specs: Grand Seiko Spring Drive U.F.A. SLGB001 And SLGB003

Movement: Self-winding Spring Drive Caliber 9RB2; 72-hour power reserve
Functions: Hours and minutes; central seconds; date
Case: 37mm ×11.4mm; High-Intensity Titanium (SLGB003) or platinum (SLGB001); 100m water-resistance
Dial: Silver-tinged blue textured dial (titanium); deeper blue textured dial (platinum)
Strap: Crocodile strap with three-fold clasp in platinum (SLGB001); High-Intensity Titanium bracelet with three-fold clasp and micro-adjustment feature (SLGB003)
Availability: Titanium is not limited; platinum is a limited edition of 80
Price: USD 39,000 (SLGB001) and USD 10,900 (SLGB003)

Find out more at Grand Seiko.

For an in-depth interactive look at the engineering marvel behind the Spring Drive U.F.A. and how Caliber 9RB2 pushes the limits of precision, watch our exclusive video breakdown on our YouTube channel.