Grand Seiko has been fairly quiet over the summer, but has just unveiled the latest addition to its Evolution 9 collection, the “Moonlit Birch” SLGW007. Effectively a new variant of the “Birch Bark” SLGW003 with a steel case and navy blue dial, the Moonlit Birch is a competent alternative to its titanium stablemate.

In other words, it’s an attractive new livery for what was already a compelling watch, and retains its best characteristics including a nuanced and ergonomic case, gorgeous dial furniture, and the brand’s latest manually wound cal. 9SA4 movement.

Initial thoughts

The original “Birch Bark” launched last year and was one of the standout releases at Watches & Wonders due to its elegant case profile and impressive new movement. The Moonlit Birch is identical in most respects, but the case is stainless steel, rather than titanium, and the dial is finished in navy blue instead of bright white.

Despite these modest differences, the Moonlit Birch is appealing in its own right. The dial texture is subtle, but it’s enough of a Grand Seiko calling card to prevent the watch from looking too generic; a common trap for time-only dress watches.

The stainless steel case exhibits the brand’s Evolution 9 styling, which gives the Moonlit Birch a bold, angular presence. In answer to the demand for slimmer options from Grand Seiko, the dimensions are nearly ideal, 38.6 mm in diameter and just under 10 mm thick.

The watch is powered by the cal. 9SA4, which is part of latest generation of Grand Seiko mechanical movements. This means it benefits from the brand’s proprietary dual-impulse escapement, which acts like a hybrid of the co-axial and traditional lever escapements, providing direct impulse in one direction, and indirect impulse in the other. The escapement is quite efficient, enabling the movement run for up to 80 hours on a full wind, despite its high frequency of 36,000 bph.

At launch, the SLGW007 is exactly US$10,000 before taxes. This is a higher price point than what Grand Seiko has historically targeted, but the Moonlit Birch has the substance to back it up and compares well against peers like the Jaeger-LeCoultre Master Control and Omega De Ville Trésor.

Evolution 9, in steel

If you put the Moonlit Birch on your wrist and close your eyes, you’d be hard-pressed to tell the difference between it and last year’s titanium SLGW003. Though the case material is steel, the difference in weight amounts to just 14 g; a 25% increase, but hardly noticeable in the real world.

Open your eyes, and it still won’t be easy, at least when it comes to the case, which retains all the rich details of its titanium sibling. This includes crisp Evolution 9 bevels and decadent facets on the insides of the lugs. Side-by-side with peers like the Master Control and De Ville Trésor, the extra work done by Grand Seiko is evident.

Frankly, the only things that tangibly diminish the overall design are the drilled lugs, which are convenient but not exactly elegant, and the bland font used for the dial text. In terms of the material itself, it would be nice to see subsequent variants delivered in the brand’s proprietary Ever-Brilliant steel, which boasts superior corrosion resistance, even compared to high-end grades of steel like 904L.

A best-in-class movement

The manually wound cal. 9SA4 is unchanged since its debut last year. Without an automatic rotor, it’s among the slimmer movements coming out of Shizukuishi but it’s not an ultra-thin movement, nor is it intended to be. Rather, it’s a highly technical caliber packed to the brim with Grand Seiko’s latest mechanical watchmaking technology.

For starters, the large free-sprung balance is secured by a full balance bridge that’s adjustable on both sides to dial in the endshake. It also features an overcoil hairspring, which is all but extinct at this price point; even Rolex appears to be moving away from this solution in favour of its own proprietary flat silicon hairspring. 

The cal. 9SA4 shown in the titanium SLGW003.

The cal. 9SA4 is pleasant to wind, and the movement-side power reserve display is a convenient addition that fits neatly in the same plane as the going train. In conjunction with the high beat rate and proprietary escapement, these features make it one of the most technically engaging movements in its segment.

Key facts and price

Grand Seiko Evolution 9 Manual-Winding Hi-Beat 36000 “Moonlit Birch”
Ref. SLGW007

Diameter: 38.6 mm
Height: 9.95 mm
Material: Stainless steel
Crystal: Sapphire
Water resistance: 30 m

Movement: 9SA4
Functions: Hours, minutes, and seconds
Winding: Manual
Frequency: 36,000 beats per hour (5 Hz)
Power reserve: 80 hours

Strap: Leather strap with folding clasp

Limited edition: No
Availability: At Grand Seiko boutiques and retailers starting October 2025
Price: US$10,000 excluding taxes

For more, visit grand-seiko.com