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Grand Seiko Evolution 9 Spring Drive U.F.A Ushio 300 Diver 40.8mm Mens Watch Green
Ref. SLGB025
Sits in Grand Seiko’s upper tier here — more premium than three quarters of the Grand Seiko watches we list, which start at £2,300.
Price range £2,300 to £10,500 across 20 Grand Seiko watches in stock.The SLGB025 belongs to a lineage of Evolution 9 divers that previously ran to 43.8mm — this generation pulls that architecture down to 40.8mm, making it the most compact Grand Seiko diver built to date, while losing none of the rated depth. The movement inside is the 9RB1, a Spring Drive hybrid developed at Grand Seiko's Shinshu Watch Studio specifically for sport conditions: it runs with the gliding, zero-beat second hand of a standard Spring Drive but is engineered to hold ±20 seconds annually, a figure that puts it beyond any conventional automatic regardless of complication count. At 12.9mm thick, the watch sits notably flat for a 300-metre-rated diver — most cases built to that depth carry considerably more height, and this one will pass under a shirt cuff where rivals will not. The High-Intensity Titanium used throughout keeps the bracelet honest on the wrist despite the 21mm lug width; a watch that reads as substantial in the hand disappears in terms of load once worn. The green dial earns the name Ushio — tide — less through colour alone than through the way its textured gradient shifts between shallow and deep readings as the light moves across it. The bracelet clasp deserves particular attention from anyone who dives with it in practice: a locking extension opens 18mm for use over a wetsuit, and the three-step micro-adjustment gives 6mm of fine-tuning in ordinary wear — a system that removes the usual compromise between a snug dry fit and a usable wet one.
- Reference
- SLGB025
- Brand
- Grand Seiko
- Collection
- Evolution 9Case Size: 40
- Case size
- 40.8mm
- Case thickness
- 12.9mm
- Lug width
- 21mm
- Case material
- Titanium
- Case shape
- Round
- Dial
- Green
- Crystal
- Sapphire
- Bezel
- Unidirectional rotating
- Movement
- Spring Drive
- Calibre
- 9RB1
- Functions
- Power reserve indicator
- Water resistance
- 300m
- Bracelet / strap
- Titanium bracelet
- Strap colour
- Silver
- Clasp
- Folding clasp
- Lume
- LumiBrite
- Retailer
- Mappin & Webb
Additional specifications
- Lug-to-lug
- 48.5mm
- Power reserve
- 72 hours
Learn more about Grand Seiko
Grand Seiko began in 1960 as Seiko's attempt to build a watch to the highest standard in the world, judged against Swiss chronometer criteria rather than Japanese ones. The first model met the Bureaux Officiels standard, and the ambition was explicit: not a good Japanese watch, but a better watch than the Swiss were making.
The 1967 Grammar of Design, laid down by Taro Tanaka, still governs the aesthetic. Flat surfaces and sharp facets rather than curves; hands and markers cut to catch light in defined planes; every surface either mirror-polished or perfectly flat, with no in-between. The polishing is done by hand on tin plates — Zaratsu — which produces distortion-free reflections and cannot be replicated by machine.
The precision case was made at observatory trials in the 1960s, where Grand Seiko movements placed among the leaders in Geneva and Neuchâtel before the competitions ended.
The house's distinctive technology is Spring Drive, introduced in 1999 after nearly three decades of development. A conventional mainspring drives the watch, but the escapement is replaced by an electromagnetic brake regulated by a quartz oscillator: mechanical power, quartz accuracy, and a seconds hand that sweeps without ticking at all.
Grand Seiko was separated into a standalone brand internationally in 2017, with dials frequently drawn from Japanese landscape — the Snowflake among the best known.
- 1960
- The first Grand Seiko is built to Swiss chronometer standards.
- 1967
- Taro Tanaka codifies the Grammar of Design.
- 1968
- The 61GS Hi-Beat reaches 36,000 vibrations per hour.
- 1999
- Spring Drive combines mechanical power with quartz regulation.
- 2017
- Established as an independent brand worldwide.
Also in 5 collections
This watch appears in Back in Stock (856), Sports Watches (696), Dive Watches (489), Green Dial Watches (380) and Titanium Watches (159).
What the specifications mean
A watch built to be worn hard and got wet.
Strengths
- 300m water resistance, rated for actual diving
- Sapphire crystal, which resists scratching
- Luminous hands and markers for low light
- One of Grand Seiko's more premium watches
Your new watch
Frequently asked questions, and things you should know about this watch
Can I swim with it?
Yes. At 300m it is rated for swimming, snorkelling and recreational diving.
Will the glass scratch?
Unlikely. Sapphire is second only to diamond in hardness and shrugs off everyday marking.
Does it need a battery?
No. Spring Drive is wound by the wrist and regulated electronically, with no battery.
How long does it run for when it's not worn?
About 72 hours fully wound — enough to sit off the wrist over a weekend and still be running.
What size strap does it take?
21mm. Any strap of that width will fit, and on most modern watches quick-release bars make the swap a two-minute job with no tools.
Will it fit my wrist?
Lug-to-lug is 48.5mm, which suits wrists from roughly 16.5cm (6½ inches) upward.
Lug-to-lug decides fit more than case diameter does.
Is it a men's or women's watch?
Listed as men's.
Cheapest place to buy
Mappin & Webb is the only UK retailer we track stocking this reference new, at £10,500. There is nothing to compare it against today.
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