Tap the image to enlarge
Grand Seiko Automatic GMT Moondrop 39.5mm Mens Watch Blue
Ref. SBGM257
See more premium optionsHide
Stepping up in the same colour and case shape
The Moondrop name belongs to a precise moment: Japanese autumn, moonlight on dew, and the geometric spiral pressed into the dial to capture how that light moves across a curved surface. It is a dial evolution of the ivory SBGM221, translated into deep navy and given a pattern that shifts from flat to almost three-dimensional as the angle of the light changes. The Zaratsu-polished case, ground to a distortion-free mirror on every surface, reinforces that interplay between light and geometry rather than competing with it. The 9S66 inside is a mechanical GMT in the truest sense: the local hour hand adjusts independently in one-hour increments at the crown's first click, leaving the movement running throughout. A 72-hour power reserve means a long weekend trip does not require winding on arrival. At 39.5mm with a 46.9mm lug-to-lug span, the case sits well on a range of wrists without the bulk that GMT complications often bring with them, and the matching dark blue crocodile strap keeps the whole thing reading as a single composed object rather than a watch on a strap.
- Reference
- SBGM257
- Brand
- Grand Seiko
- Collection
- Elegance CollectionCase Size: 39
- Case size
- 39.5mm
- Case thickness
- 14.1mm
- Lug width
- 19mm
- Case material
- Stainless steel
- Case shape
- Round
- Dial
- Blue
- Crystal
- Sapphire
- Movement
- Automatic
- Calibre
- 9S66
- Functions
- GMT, Date
- Water resistance
- 30m
- Bracelet / strap
- Leather strap
- Strap colour
- Blue
- Clasp
- Folding clasp
- Lume
- Luminous
- Retailer
- Mappin & Webb
Additional specifications
- Lug-to-lug
- 46.9mm
- 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 6 collections
This watch appears in Stainless Steel Watches (2,846), Automatic Watches (1,468), Leather Strap Watches (938), Back in Stock (856), Blue Dial Watches (776) and Dress Watches (459).
What the specifications mean
A mechanical watch for everyday wear.
Strengths
- 39.5mm suits most wrists
- Sapphire crystal, which resists scratching
- 72-hour reserve survives a weekend off the wrist
- Luminous hands and markers for low light
- Second time zone for travelling
Worth knowing
- 30m means keeping it away from water
- 14.1mm thick, so it will not disappear under a cuff
Compare alternatives
Watches from other brands at a similar price, style and size, so you can see what else your budget can buy.
| Specification | SBGM257 | 34238AA54.BVA95 | L27935727 |
|---|---|---|---|
| Price | £4,550 | £4,500 | £3,800 |
| Case size | 39.5mm | 39mm | 40mm |
| Water resistance | 30m | 50m | 30m |
| Movement | Automatic | Automatic | Automatic |
| Strap | Leather strap | Leather strap | Stainless steel bracelet |
| Power reserve | 72 hours | 38 hours | 72 hours |
| This watch |
|
|
Your new watch
Frequently asked questions, and things you should know about this watch
Can I swim with it?
No. At 30m it will survive rain and handwashing, but not submersion of any kind.
Will the glass scratch?
Unlikely. Sapphire is second only to diamond in hardness and shrugs off everyday marking.
Does it need a battery?
No. It is automatic — the motion of your wrist winds it, and there is no cell to replace.
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?
19mm. 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 46.9mm, which suits wrists from roughly 16cm (6¼ 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, though at 39.5mm it sits in the range that suits anyone.
Cheapest place to buy
Mappin & Webb is the only UK retailer we track stocking this reference new, at £4,550. There is nothing to compare it against today.
You may also like
In stock, and close on style and price
