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Grand Seiko Evolution 9 Spring Drive U.F.A Ushio 300 Diver 40.8mm Mens Watch Blue
Ref. SLGB023
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 23 Grand Seiko watches in stock.Grand Seiko's dive watches have historically asked a great deal of the wrist — the SLGA023 that preceded this ran to 43.8mm, substantial even by modern standards. The SLGB023 is the answer to that: same Evolution 9 architecture, same 300-metre rating, but drawn tighter and built in high-intensity titanium so that at 122 grams it wears more like a daily watch than a piece of diving equipment. At 12.9mm thick it sits flatter under a cuff than almost anything rated this deep, which changes who can actually live with it. The 9RB1 is made at the Shinshu Watch Studio, where Grand Seiko hand-finishes its more demanding calibres, and it carries the U.F.A. designation — Ultra Fine Accuracy — which in practice means ±20 seconds across a full year. That figure comes from the Spring Drive's glide-wheel regulation rather than a conventional lever escapement, and the 9RB1 adds a personal adjustment mechanism so the owner can trim the rate themselves, a first for any Spring Drive. The dial earns its look: the wave-relief surface under the gradient blue is a physical texture, not a printed effect, and it shifts character entirely in low light once the LumiBrite indexes take over. The bracelet clasp adjusts tool-free in 2mm increments and extends a further 18mm for a suit, the sort of hardware detail that separates a watch built for the water from one merely rated for it.
- Reference
- SLGB023
- Brand
- Grand Seiko
- Collection
- Evolution 9 CollectionCase Size: 40
- Case size
- 40.8mm
- Case thickness
- 12.9mm
- Lug width
- 21mm
- Case material
- Titanium
- Case shape
- Round
- Dial
- Blue
- 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
- Three-fold 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 (1,176), Blue Dial Watches (696), Sports Watches (649), Dive Watches (461) and Titanium Watches (152).
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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