Grand Seiko has had a rather eventful few years, to put it mildly. It took the pursuit of chronometry to a very technical high with the magnificent Kodo Constant-Force Tourbillon that combined two regulating devices in a co-axial configuration. It also introduced the hi-beat 9SA5, which brought to market the Dual Impulse Escapement, the first escapement since the Co-Axial to be conceived with a level of practicality and maturity required for industrial production.

On the design side of things, there has also been a significant evolution, particularly within the aptly named Evolution 9 collection, first unveiled in 2020 during the brand’s 60th anniversary. The watches in this collection are overall slimmer than other Grand Seiko models, owing to the thinner mechanical and Spring Drive movements within. Their cases represent an evolution of the iconic 44GS design. While the self-winding 9SA5 and the newly introduced hand-wound 9SA4 movements have pretty much become the posterchildren of the collection, the range also includes the self-winding Spring Drive 9RA2, which, in a move to address a common pet peeve among Spring Drive enthusiasts, relocated the power reserve indicator from the dial to the movement plate. The 9RA2-equipped watches in the collection are also significant as they represent the slimmest Grand Seiko Spring Drive watches.

Today, the brand has unveiled the SLGA025 “Atera Blue”, which is only the fourth regular production model in the Evolution 9 collection that is equipped with the Spring Drive 9RA2 movement.

Grand Seiko has always been known to enthusiasts for the beauty of its nature-inspired dials, and the SLGA025 takes inspiration from the Atera Valley of Shinshu, nestled within the Japanese Alps not far from Grand Seiko’s Shinshu Watch Studio, where all Spring Drive watches are made. Renowned for its crystal-clear emerald-green waters, the valley is defined by the Atera River, which flows through a series of narrow gorges and tranquil pools, bordered by lush forests and striking rock formations. The SLGA025 is the second model this year inspired by a Japanese valley, following the SLGH021 “Genbi Valley.”

The dial showcases a new stamped pattern with intricate, fine scratches that creates the impression of the river’s flow. This design is enhanced by a graduated finish that dynamically changes with light, transitioning from a mesmerising emerald turquoise to a deep forest green. The effect, at least from some real-life photographs, seems to have very successfully captured the depth and texture of a river as light hits its surface. Like the SLGH models, it has a sharply truncated hour hand, as well as very elaborate grooved and faceted indexes on the dial.

The case is in high-intensity titanium, a hardened titanium alloy with all the corrosion resistance, lightness, and hypoallergenic properties of standard titanium, but with much greater scratch resistance. The SLGA025 is only the second 9RA2-equipped SLGA model to be executed in titanium; the other being the SLGA019 “Lake Suwa.” It measures 40mm wide and 11.8mm high, just 0.1 thicker than the SLGH models. The case design is much more modern and elegant compared to the iconic 44GS and the finishing is exemplary. There are numerous facets that lend themselves to alternating satin-brushing and Zaratsu polishing. It is paired with a high-intensity titanium bracelet. A common gripe with Grand Seiko bracelets is that they are not tapered, but they are generally very comfortable to wear.

The self-winding 9RA2 is exactly the same as the 9RA5 in construction and performance while relocating the power reserve indicator to the movement side. It offers a power reserve of 120 hours (5 days) using two serially coupled barrels. To make the most of available space, the two barrels are of different sizes, with one being much larger than the other. The self-winding mechanism relies on an “offset magic lever” system, which as its name suggests, is implanted away from the centre of the movement to reduce its thickness.

It bears repeating that the Spring Drive is an electromechanical movement that was invented to circumvent the issues faced with components that will eventually deteriorate with time – the lever escapement in a mechanical watch and the batteries and electrolytic capacitors in a quartz watch – while offering an accuracy superior to that of a mechanical watch. It has an entirely conventional wheel train, but in place of an escapement is a glide wheel which, with the help of two tiny electromagnets, controls the speed at which the mainspring unwinds. By spinning, it generates electrical power which then activates an integrated circuit and a quartz oscillator.

The quartz oscillator vibrates at a frequency of 32,768 Hz, transmitting a precise reference signal to the integrated circuit. Meanwhile, the integrated circuit has a logic circuit that compares the reference signal with the speed of rotation of the glide wheel and exerts a braking force on the glide wheel when it is spinning too fast to maintain a rate of eight revolutions per second. Because the glide wheel turns smoothly, as opposed to a traditional lever escapement that provides the characteristic “tick tock”, the entire gear train advances in a smooth, continuous motion. This is reflected in the gliding motion of the seconds hand which can’t be replicated with anything else.

Tech Specs

Movement: Spring Drive 9RA2 Automatic; 5-day power reserve; ±10 seconds per month (±0.5 second per day)
Functions: Hours, minutes, seconds, date
Case: High-intensity titanium; 40mm x 11.8mm; 100m water resistance
Bracelet: High-intensity titanium bracelet with three-fold clasp and push-button release
Availability: Regular production model; available at all Grand Seiko boutiques and authorised retailers in September
Price: USD 10,500, or SGD 14,000