In today’s tech-saturated world, one could argue that the precision of a mechanical wristwatch is inconsequential. And yet, the pursuit of even greater accuracy remains a hallmark of serious watchmaking, with Swiss manufactures reinforcing their commitment through COSC- and METAS-certifications for both technical assurance and collector confidence. Japanese luxury brand Grand Seiko has its own rigorous in-house testing standards, which some consider to be even more stringent.
Since its founding in 1960, Grand Seiko has pursued extraordinary accuracy, a legacy exemplified by the “Very Fine Adjusted” (VFA) designation first applied in 1969 to mechanical watches that achieved an impressive ±1 minute a month. Building on this commitment, Grand Seiko began research and development on the “Prius” of movements in the early 1970s.
Earlier this year, I spoke to Ikukiyo Komatsu, the highly decorated master watchmaker and head of in-house training at Grand Seiko’s Shinshu Watch Studio in Shiojiri. Komatsu pointed out that the first hand-wound Spring Drive movement reference 7R68 was presented in 1999 at Basel World. It featured a hybrid system that combined the torque of the mainspring found in conventional mechanical watches with the precision of electronic timekeeping. Using this traditional means of generating power eliminates the need for a battery as energy from the mainspring is transferred to gears and moves the seconds hand in the smooth, gliding motion that is a signature of Spring Drive. This is a mechanical movement in almost every sense except that you won’t find a fiddly lever escapement in a Spring Drive. Instead, a “Tri-Synchro Regulator” is used to synchronise the mechanical movement and a quartz crystal oscillator.
This patented regulator produces a tiny electrical pulse created by the movement of the mainspring, transforming it into energy that triggers a crystal oscillator. The oscillator then sends an exact reference signal to the integrated circuit (IC), which applies a magnetic brake to ensure that the speed of its glide wheel is exactly eight revolutions a second. This accuracy is conveyed through a gear train to the watch hands. In 2004, the Spring Drive Caliber 9R65 was presented in an SBGA series watch, setting a new standard with automatic winding, a 72-hour power reserve, and accuracy within ±15 seconds a month.
This must have been quite a disruptive concept for traditionalists but “for those who put accuracy first”, it was groundbreaking. The 9R65 became the base movement for their chronograph and GMT calibres with increased efficiency and power reserve over time.
According to Komatsu, the Swiss had played around with similar ideas at the time, but nothing went into production. However, something similar was presented by Piaget in 2016 to celebrate the 40th anniversary of their first in-house quartz movement: The Emperado Coussion XL 700P featured an ultra-thin, self-winding mechanism with high-precision generator.
During our interview, Komatsu wore his Evolution 9 with a magnificent rippled blue dial evoking the gentle waves on Lake Suwa near his home and the Shinshu Watch Studio where the Spring Drive watches are made. Inside his watch (ref SLGA019) is the Calibre 9RA2, introduced in 2021 with its slimmer profile, five-day power reserve, and with an accuracy of ±10 seconds a month.
The latest Spring Drive Caliber 9RB2 continues the legacy and is the first to carry the new Ultra Fine Accuracy (UFA) designation, featured on the dial of the new Evolution 9 model to indicate an impressive ±20 seconds precision a year. According to Komatsu, this is the highest level of accuracy ever achieved in a mainspring-powered wristwatch. The design of the Evolution 9 Collection is a contemporary expression of Grand Seiko’s design philosophy, rooted in the iconic 44GS of 1967. The calibre’s compact design allows for a vintage-sized 37mm case — the smallest yet in the 9R series — offering both exceptional performance and refined proportions.
Komatsu is the second generation of watchmakers in his family and with over four decades of experience in the industry has been recognised as a “Modern Master Craftsman” by the Japanese government. In his collection is an original Seiko Laurel from 1913, left to him by his late father who worked at Seiko, and who inspired Komatsu from a very young age to follow in his footsteps. With incredible prowess, he provided a deeper understanding of the 9RB2 for me by meticulously disassembling and reassembling one of these movements.
The leap in precision of the 9RB2 is achieved through a newly designed low-power IC, more refined processing methods and three-month “ageing” of the quartz oscillator, and thermal compensation that is calibrated individually for each oscillator. The ageing is a costly but key quality-control process for high-end quartz that allows the crystals to stabilise prior to assembly. Quartz crystals are not 100% stable immediately after manufacturing so over time their oscillation frequency can shift slightly as the internal structure settles, which, in turn, can affect timekeeping.
This process filters out crystals prone to drift and therefore enhances performance. Each selected quartz crystal is then tested across various temperatures for precise thermo-compensation data to be programmed into the IC to guarantee consistent performance regardless of external temperature changes. All components are then vacuum-sealed to ensure resistance against humidity, light, and static, for long-term stability. For the first time, the 9RB2 also features a regulation switch that allows for fine-tuning during servicing to maintain peak accuracy over time.
The team frequently draws inspiration from the natural environment as part of the Grand Seiko design philosophy, especially in the play of light and shadow, as captured so eloquently in their dial finishes. One of my favourite pieces at Watches & Wonders Geneva this year was the titanium reference SLGB003 with its silvery blue dial. These textured dials capture the splendour of the frost-covered forests in the Kirigamine Highlands east of the Shinshu studio during winter months.
Other features include a box-shaped sapphire crystal, date window at 3 o’clock, tempered blue seconds hand, titanium bracelet with new micro-adjustable clasp, and a sapphire caseback revealing the beautifully finished movement and a power reserve indicator. Limited to 80 pieces, there is also a platinum 950 reference SLGB001 with a crocodile strap and a slightly deeper blue dial. Cases feature the studio’s signature Zaratsu polishing with a mirror finish. Both watches are water resistance to 100m and have magnetic resistance to 4800 A/m.
POA, grand-seiko.com or Treger Group for local retailers 010 142 4480
