Grand Seiko Evolution 9 "Moonlit Birch" Hi-Beats hand-wound blue dial leather strap 38,6 mm

Introduction & Collection

In 2021, the Grand Seiko “White Birch” introduced a new aesthetic language that would leave a lasting mark on contemporary watchmaking: the Evolution 9 Style. This reimagined design, both modern and deeply rooted in Japanese codes, quickly established itself as one of the brand’s major signatures. Since then, the collection has grown with numerous variations, from the SLGH005 to the SLGA009, culminating in 2024 with a slimmer, more elegant interpretation equipped with Grand Seiko’s first hand-wound Hi-Beat movement in over 50 years: the Caliber 9SA4, launched in the SLGW002 (18K rose gold) and SLGW003 (titanium) models.

In 2025, the story continues with the SLGW007 “Moonlit Birch,” which retains the refined design of its predecessors but now comes in a stainless-steel case. Measuring 38.6 mm in diameter and just 9.95 mm thick, it is the thinnest mechanical Evolution 9 ever created, while gaining presence and balance on the wrist thanks to the transition from titanium to steel. More accessible than the earlier editions, it stands as an elegant, versatile, and truly universal interpretation of the Evolution 9 Style.

Its deep navy-blue textured dial reprises the iconic birch-bark pattern, a true embodiment of the brand’s Nature of Time philosophy. Inspired by the birch forests of the Hiraniwa Plateau in Iwate Prefecture—where Grand Seiko mechanical watches are crafted—the “Moonlit Birch” transposes this familiar landscape into a nocturnal atmosphere. The shifting reflections of the dark blue surface evoke the sight of a white birch faintly revealed in the moonlight, imbuing the watch with an aura that is both serene and mysterious.

Design & Dial

The SLGW007 “Moonlit Birch” faithfully expresses the Evolution 9 Style, but adapts it into a slimmer and more formal format. Its stainless-steel case, 38.6 mm in diameter and 9.95 mm thick, retains the sharp, faceted lines characteristic of Grand Seiko, alternating between Zaratsu polishing and brushed finishes. Compared with the titanium SLGW003, the use of steel brings greater weight and presence to the wrist, enhancing both balance and refinement.

The bezel has been subtly thinned, creating a wider dial opening that improves legibility while highlighting the textured surface. The elongated, angular lugs echo the rhythm of the applied indexes and extend the overall harmony of the design. The profile, enhanced by a box-shaped sapphire crystal with anti-reflective coating, adds visual depth without compromising the watch’s slim, contemporary silhouette.

The dial itself is the true centerpiece. Inspired by the white birch forests of the Hiraniwa Plateau, its irregularly textured surface recreates the bark of these emblematic trees, now a hallmark of the brand. Here, the texture first introduced with the SLGW003 is reinterpreted in a deep navy hue, evoking the vision of tree trunks illuminated by moonlight. Depending on the light, the surface alternates between shadowed tones and silvery highlights, creating a living, poetic aesthetic in perfect resonance with the Nature of Time philosophy.

The silver-toned hands and indexes, with razor-sharp facets and mirror polishing, capture the light with precision and underscore the refined character of the watch. Completing the ensemble is a textured cowhide strap whose tone and irregularities subtly echo the dial. More contemporary than a traditional alligator strap, this choice brings a touch of elegant casualness, perfectly suited to everyday wear.

Movement & Technique

The SLGW007 is powered by the Caliber 9SA4, a hand-wound mechanical movement beating at a high frequency of 36,000 vibrations per hour and offering an impressive power reserve of approximately 80 hours. Based on the automatic 9SA5 introduced in 2020, it inherits its key innovations while being extensively re-engineered: nearly 40% of its architecture has been redesigned to transform the act of winding into a truly sensory experience.

Each turn of the crown produces a crisp feel and a distinct sound, the result of meticulous adjustments to the click and its spring. The crown naturally halts once the mainspring is fully wound, ensuring both comfort and safety. The transparent caseback reveals a discreet power reserve indicator, preserving the purity of the dial while allowing the wearer to monitor the remaining energy.

Beyond its chronometric performance—achieving an accuracy of +5/-3 seconds per day in static conditions and -1/+8 seconds in daily use—the 9SA4 stands out for its aesthetic and symbolic depth. The click, shaped like a wagtail bird, pays tribute to the species native to the Shizukuishi region where Grand Seiko’s mechanical studio is located. Its movement, visible during winding, recalls the graceful motion of the bird itself. The refined decorations, inspired by the Shizukuishi River, further emphasize the close bond between this caliber and the natural environment from which it draws inspiration.

Tested over seventeen days in six positions and at three different temperatures, the 9SA4 exemplifies Grand Seiko’s uncompromising standards of reliability and durability. Combining cutting-edge innovation, natural inspiration, and the joy of interaction, it embodies both the technical mastery and the poetic soul of the brand.