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Seiko King Seiko KSK 'Charcoal Suit' 38.3mm Mens Watch Grey
Ref. SPB387J1
Sits in Seiko’s upper tier here — more premium than three quarters of the Seiko watches we list, which start at £110.
Price range £110 to £3,550 across 192 Seiko watches in stock.The sharp, angular case follows the classic KSK silhouette, measuring 38.3mm across and sitting just 11.7mm thick on the wrist. Stainless steel surfaces combine hairline and mirror finishes, and the screw-down caseback carries an embossed King Seiko crest. A box-shaped sapphire crystal with inner anti-reflective coating sits above the charcoal grey dial, which carries a vertical brushed hairline finish. LumiBrite is applied to both hands and hour indices. The multi-link bracelet attaches via a dual-lever quick-release system at the end-pieces, allowing toolless removal. A push-button deployment clasp secures the fit. Inside runs the 6R55 automatic calibre, offering a 72-hour power reserve and hacking seconds.
- Reference
- SPB387J1
- Brand
- Seiko
- Collection
- King Seiko
- Case size
- 38.3mm
- Case thickness
- 11.7mm
- Case material
- Stainless steel
- Case shape
- Round
- Dial
- Grey
- Crystal
- Sapphire
- Movement
- Automatic
- Calibre
- 6R55
- Functions
- Date
- Water resistance
- 100m
- Bracelet / strap
- Stainless steel bracelet
- Strap colour
- Silver
- Clasp
- Deployant clasp
- Lume
- LumiBrite
- Retailer
- Mappin & Webb
Additional specifications
- Lug-to-lug
- 46mm
- Power reserve
- 72 hours
- Weight
- 139g
Learn more about Seiko
Kintaro Hattori opened a watch and clock shop in Tokyo in 1881, aged twenty-one, and began manufacturing under the name Seikosha — roughly, house of exquisite workmanship — in 1892. The Seiko name appeared on watches from 1924.
The company's significance is that it broke the Swiss monopoly twice. First on precision: Seiko was appointed official timekeeper of the 1964 Tokyo Olympics and built the quartz chronometers and printing timers to do it, and in the 1960s its movements placed highly at the Neuchâtel and Geneva observatory trials against the best Swiss houses.
Then on technology. On Christmas Day 1969 Seiko released the Astron, the world's first quartz wristwatch, accurate to five seconds a month where mechanical watches managed that per day. The consequences for Switzerland were catastrophic — employment in the Swiss industry fell by roughly two-thirds over the following decade. Seiko deliberately did not enforce its quartz patents, allowing the technology to spread.
The same year it produced the 6139, among the first automatic chronographs, and it has since introduced Kinetic, Spring Drive — a hybrid regulating a mechanical mainspring electronically, giving a perfectly gliding seconds hand — and its own dive and field lines.
Seiko remains fully vertically integrated, making its own hairsprings, quartz crystals, and even the Zaratsu-polished cases, at price points from under a hundred pounds upward.
- 1881
- Kintaro Hattori opens his Tokyo shop.
- 1924
- The first watches carry the Seiko name.
- 1964
- Official timekeeper of the Tokyo Olympics.
- 1969
- The Astron becomes the first quartz wristwatch.
- 1999
- Spring Drive enters production.
Also in 3 collections
This watch appears in Stainless Steel Watches (3,157), Automatic Watches (1,753) and Grey Dial Watches (247).
Temporarily out of stock
Goldsmiths is not currently taking orders for this reference. Last listed as available on 3 September 2026. Stock is checked nightly and this page updates when it returns.
What the specifications mean
A mechanical watch for everyday wear.
Strengths
- 100m water resistance covers swimming and watersports
- 38.3mm suits most wrists
- Sapphire crystal, which resists scratching
- 72-hour reserve survives a weekend off the wrist
- Luminous hands and markers for low light
Seiko King Seiko KSK 'Charcoal alternatives
Watches from other brands at a similar price, style and size, so you can see what else your budget can buy.
| Specification | SPB387J1 | R12160103 | 68035A77 |
|---|---|---|---|
| Price | £1,350 | £1,400 | £1,450 |
| Case size | 38.3mm | 38mm | 38mm |
| Water resistance | 100m | 100m | 100m |
| Movement | Automatic | Automatic | Automatic |
| Strap | Stainless steel bracelet | Stainless steel bracelet | Stainless steel bracelet |
| Power reserve | 72 hours | 80 hours | — |
| This watch | Closely matched | Closely matched |
Your new watch
Frequently asked questions, and things you should know about this watch
Can I swim with it?
Yes. At 100m it is rated for swimming and snorkelling, though not for diving.
Water resistance explainedWill the glass scratch?
Unlikely. Sapphire is second only to diamond in hardness and shrugs off everyday marking.
Sapphire, mineral and acrylic comparedDoes it need a battery?
No. It is automatic — the motion of your wrist winds it, and there is no cell to replace.
Quartz, automatic and solar comparedHow 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.
Will it fit my wrist?
Lug-to-lug is 46mm, which suits wrists from roughly 16cm (6¼ inches) upward.
Lug-to-lug decides fit more than case diameter does.
How to size a watch to your wristIs it a men's or women's watch?
Listed as men's, though at 38.3mm it sits in the range that suits anyone.
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