Grand Seiko Evolution 9 Ushio 300 Diver Green
SLGB025
- Case
- 40.8mm
- MSRP
- $12,400
- Movement
- Spring Drive
- Reserve
- 72h
VS
Building 1v1 comparison
Building 1v1 comparison
1v1 Watch Comparison
A focused side-by-side page for specs, fit, movement details, review notes, and enthusiast context.
SLGB025
HBB001
Pair Review
Built from the saved specs and wearability notes for these two watches, then weighed against enthusiast priorities like fit, movement quality, practicality, finishing, value, and collector appeal.
Where it wins
Wins for buyers who prefer its overall mix of specs, fit, ownership appeal, and value.
Where it wins
Wins for buyers who prefer its overall mix of specs, fit, ownership appeal, and value.
The Grand Seiko uses the Spring Drive caliber 9RB1, a technically distinctive mainspring-powered movement with a 72-hour power reserve and a stated accuracy of ±20 seconds per year, which is exceptional on the provided data. The Seiko Prospex uses the automatic 4R35 with manual winding, 23 jewels, and a 41-hour power reserve; no accuracy claim is listed. In enthusiast terms, the Grand Seiko offers a far more sophisticated movement concept and a much stronger precision claim, while the Seiko’s movement is a proven, simpler workhorse with more conventional ownership expectations. Serviceability and long-term reliability are not specified, so they cannot be compared directly beyond the relative simplicity of the 4R35 versus the more advanced Spring Drive. Winner: Grand Seiko
The Grand Seiko measures 40.8mm across, 12.9mm thick, and 48.5mm lug-to-lug, with a 122g titanium case and bracelet, which should translate to notably lighter, more balanced wrist presence. The Seiko Prospex is slightly larger at 41.7mm, thinner at 12.3mm, and longer at 49.5mm lug-to-lug, but its stainless steel construction brings the weight to 170g, making it feel substantially more substantial on wrist. The Grand Seiko wearability notes specifically say it wears slimmer and lighter than previous GS divers and is among the most comfortable luxury divers in its class, helped by a proper micro-adjust clasp. The Prospex is described more simply as a compact diver with classic dimensions and 200m water resistance. For comfort and refined fit, the Grand Seiko has the edge; for those who prefer a more traditional steel diver presence, the Seiko will feel more tool-like. Winner: Grand Seiko
The Grand Seiko offers a green Ushio gradient dial, sapphire crystal with inner anti-reflective coating, LumiBrite, a unidirectional rotating bezel, 300m water resistance, and a locking extension clasp with 6mm micro-adjustment. The Seiko Prospex has a silver white dial with Seiko Blue accents, Hardlex crystal, LumiBrite on hands, indexes, and bezel, a date display, a unidirectional bezel, 200m water resistance, and a three-fold clasp with secure lock, push-button release, and extender. In practice, the Grand Seiko is the more legible and premium-feeling package, with stronger underwater credentials and a more refined clasp system; it is also praised in the wearability notes for excellent legibility and a balanced, purposeful design. The Seiko adds a date and full lumed bezel, which can be useful in everyday and sports contexts, and it is the simpler, more casual tool watch. On materials, finishing, and overall execution, the Grand Seiko is clearly superior; on straightforward everyday utility and lower-stakes wear, the Seiko remains very practical. Winner: Grand Seiko
At $12,400, the Grand Seiko is a high-end luxury diver that leans on titanium construction, Spring Drive technology, and strong finishing/brand-signature appeal. At $595, the Seiko Prospex is dramatically more accessible while still offering a solid steel diver format, limited edition marking on the case back, and a recognizable Prospex tool-watch identity. The Grand Seiko’s ownership appeal is about craftsmanship, movement innovation, and collector distinction; the Prospex’s appeal is about low-cost entry, daily practicality, and a limited-edition angle without the financial commitment. Maintenance expectations are not listed, so they cannot be compared directly. In pure value terms, the Seiko is the clear winner by affordability, while the Grand Seiko offers the more elevated collector experience if the budget is part of the equation. Winner: Seiko Prospex
Compared
SLGB025
HBB001