Grand Seiko has introduced a new limited edition model to its Evolution 9 Collection, the SLGB005. This release centers on a new movement, the Caliber 9RB2, which earns the designation of "Ultra Fine Accuracy," or U.F.A. The watch is also defined by its distinct violet-colored dial, which finds its inspiration in the natural scenery of the Shinshu region in Japan, where the brand's Spring Drive watches are produced. This piece combines a high level of technical achievement with an aesthetic deeply rooted in the Japanese appreciation for the subtleties of nature.
The philosophy of Grand Seiko has long been guided by a dedication to achieving the highest levels of accuracy, legibility, and refined beauty. Since its first watch was created in 1960, the brand has consistently pursued the ideal timepiece, a pursuit that has led to significant advancements in both mechanical and electronic watchmaking. This dual expertise is unique in the industry and culminated in the creation of Spring Drive, a technology that harmonizes the motive force of a traditional mainspring with the precision of an electronic regulator. The SLGB005 and its Caliber 9RB2 are direct descendants of this legacy, pushing the boundaries of what is possible for a mainspring-powered watch.
Courtesy of Grand Seiko
The design of the SLGB005 is governed by the principles of the Evolution 9 Style. This design grammar is a modern reinterpretation of the Grand Seiko Style established with the 44GS model in 1967. The Evolution 9 Style is built on three core pillars. The first is a focus on aesthetics and the Japanese sensibility of light and shadow, achieved through complex, multi-faceted cases with contrasting surface finishes. The second is legibility, ensuring that the time can be read clearly and instantly through the use of prominent, grooved indexes and substantial, differentiated hands. The third pillar is wearer comfort, with designs that feature a low center of gravity and bracelets engineered for a secure and balanced fit.
Applying these principles, the case of the SLGB005 is crafted from Ever-Brilliant Steel, a stainless-steel alloy with exceptional corrosion resistance and a noticeably bright, whitish hue compared to conventional steel. This material choice not only ensures the watch's longevity but also accentuates the sharp, crisp lines of the case and the flawless finish of the Zaratsu polishing. This polishing technique, a hallmark of the brand, creates distortion-free mirror surfaces that contrast sharply with delicate hairline brushing, allowing the case to interact with light in a dynamic and captivating way.
The dimensions of the case are a compact 37.0mm in diameter with a thickness of 11.4mm and a lug-to-lug measurement of 44.3mm. These proportions, combined with the low center of gravity inherent in the Evolution 9 design, make for a watch that is exceptionally comfortable and well-suited for a wide range of wrist sizes. The case is equipped with a screw-down crown and provides a water resistance of 10 bar, or 100 meters, ensuring its durability for everyday wear. The overall construction feels solid and meticulously engineered, a direct reflection of the brand’s manufacturing standards.
Courtesy of Grand Seiko
The most immediately striking feature of the SLGB005 is its dial. The inspiration comes from a specific natural phenomenon observed in the Kirigamine Highlands, east of the Shinshu Watch Studio. During the harsh winters, the trees in the forests become covered in frost. The dial captures the brief, ethereal moment at dawn when the first light hits these frost-covered trees, causing them to glow in a subtle violet color. This scene is translated onto the watch face through a complex finishing process that creates an intricate, crystalline texture.
The dial's color is not a flat violet but features a gradual transition, with a deeper hue at the periphery that lightens toward the center. This gradient effect reveals more of the underlying texture in the middle of the dial, creating a sense of depth and evoking the image of the forest slowly becoming visible as the morning light grows stronger. The dial serves as a backdrop for the smooth, silent glide of the silver-toned seconds hand, a motion unique to Spring Drive that mirrors the quiet and continuous passage of time.
Legibility is paramount in the Evolution 9 Style, and the hands and indexes of the SLGB005 are designed accordingly. The hour and minute hands are broad and multi-faceted, with brushed top surfaces and polished, beveled edges. The hour markers are similarly prominent and three-dimensional, with a deep groove running down their center. This complex geometry ensures that the hands and markers catch even the faintest light, creating strong contrast against the textured dial and allowing the time to be read accurately at a glance from any angle. A framed date window sits at the 3 o'clock position, maintaining the dial's functional balance.
Courtesy of Grand Seiko
At the heart of this timepiece is the new Spring Drive Caliber 9RB2. This movement introduces the "Ultra Fine Accuracy" (U.F.A.) standard to the Grand Seiko lineup, boasting an astonishing accuracy rate of ±20 seconds per year. This level of precision, which translates to approximately ±3 seconds per month, sets a new benchmark for a wristwatch powered by a mainspring. This achievement is the result of several key technological enhancements and a meticulous manufacturing process.
The accuracy of the Caliber 9RB2 is built upon the foundation of Spring Drive technology, which uses a mainspring to power the gear train. At the end of the gear train, instead of a traditional escapement, a glide wheel rotates and generates a small electrical current. This current powers an integrated circuit (IC) and a quartz oscillator, which in turn regulates the speed of the glide wheel with extreme precision. This hybrid system offers the autonomy of a mechanical watch with the accuracy of a high-end quartz watch.
To reach the U.F.A. standard, Grand Seiko refined this system considerably. The process begins with the quartz oscillator itself, which is grown in-house and aged for three months to ensure its stability. Only the most stable oscillators are selected for the 9RB2. These are paired with a newly designed, low-power IC that includes a temperature sensor. The sensor measures the ambient temperature 540 times a day, and the IC uses this data to compensate for the tiny variations in the quartz crystal's frequency caused by temperature changes.
To further enhance stability, both the quartz oscillator and the IC are housed together in a single, vacuum-sealed package. This measure protects the components from external factors like humidity, static electricity, and light, all of which can affect performance. It also eliminates any temperature difference between the oscillator and the sensor, allowing for more precise thermal compensation and ensuring the movement's accuracy remains stable over time.
Courtesy of Grand Seiko
A significant innovation in the Caliber 9RB2 is the inclusion of a regulation switch, a first for any Spring Drive movement. While the movement is designed for long-term stability, this switch allows for the correction of any minor deviations in accuracy that might occur after many years of use. This feature can be utilized during after-sales service, ensuring that the watch can be maintained to its original high standard of precision throughout its life.
The physical architecture of the Caliber 9RB2 was also designed with purpose. It is a relatively compact movement, with a diameter of 30mm and a thickness of 5.02mm, which enables the use of the smaller 37mm case. This was achieved through the development of a thin single barrel, which still provides a power reserve of approximately 72 hours, and a new Magic Lever winding system with an offset crank wheel. The movement's robustness is ensured by a "One-piece Center Bridge" structure, which securely holds the gear train in place and contributes to the watch's low center of gravity.
The finishing of the movement, visible through the sapphire crystal case back, is also inspired by the natural environment of Shinshu. The design of the bridges is meant to represent the gentle frost that covers the region's trees in winter. The surfaces are treated with a neutral-toned sandblast coating that provides a calm, uniform texture. The edges of the bridges are diamond-cut to a sharp, brilliant finish, creating a striking contrast and capturing light from any angle.
The jewels set within the movement are intended to evoke the glittering stars seen in the clear winter skies above the mountains of Shinshu. The oscillating weight is specially engraved with the words "Ultra Fine Accuracy," clearly identifying the movement's high-performance specification. This level of decorative detail underscores the fact that in a Grand Seiko timepiece, every component, whether visible or hidden, is finished to an exceptionally high standard.
Courtesy of Grand Seiko
The watch is fitted with a bracelet also crafted from Ever-Brilliant Steel, with a design that contributes significantly to the overall comfort. The bracelet is substantial, with a width that is more than half the diameter of the case, a proportion that helps to balance the watch head securely on the wrist. It fastens with a three-fold clasp equipped with a push-button release mechanism. The clasp itself incorporates parts made from both titanium and 18K rose gold, a subtle detail that adds another layer of material refinement to the piece.
The Grand Seiko Evolution 9 Collection SLGB005 will be available as a limited edition of 1,300 pieces. It is scheduled for release in November 2025 through Grand Seiko Boutiques and select retail partners worldwide. The recommended retail price is set at $11,100 USD.
Case: Ever-Brilliant Steel, 37.0mm diameter, 11.4mm thickness, 44.3mm lug-to-lug. Box shaped sapphire crystal with anti-reflective coating. See-through screw-down case back, screw-down crown. Water resistance 10 bar, magnetic resistance 4,800 A/m.
Movement: Spring Drive Caliber 9RB2, automatic with manual winding. 72-hour power reserve, 34 jewels. Accuracy of ±20 seconds per year (±3 seconds per month). Features a power reserve indicator and a regulation switch.
Dial: Textured violet-colored dial with a gradient that lightens towards the center. Inspired by frost-covered forests in the Shinshu region. Features prominent, multi-faceted hands and grooved indexes of the Evolution 9 Style.
Strap: Ever-Brilliant Steel bracelet with a 20mm band width. Three-fold clasp with push button release, made partly of titanium and 18K rose gold.
Price: $11,100.00
Reference Number: SLGB005
Notes: Limited edition of 1,300 pieces. The movement features the "Ultra Fine Accuracy" (U.F.A.) designation, making it the most accurate mainspring-powered wristwatch movement from the brand. It is the first Spring Drive to include a regulation switch for long-term accuracy adjustments.