Front view
Dial, hands and bezel as delivered.
Case-back view
Case-back engraving and, where fitted, the sapphire display.
Movement
Calibre with its finishing and decoration.
On the wrist
Worn shot for proportion and strap drape.
Seiko · King Seiko
Seiko King Seiko 38 mm Slate 18k
Reference 91545OR.66
Reference at a glance
- Brand
- Seiko
- Collection
- King Seiko
- Model
- Seiko King Seiko 38 mm Slate 18k
- Reference number
- 91545OR.66
- Year / era
- 1986 · 1980s — mechanical revival
- Complication
- Moon phase
- Movement
- Automatic, 24 jewels
- Case material
- 18k yellow gold
- Dial type
- Slate grey
- Strap / bracelet
- Jubilee bracelet
- Water resistance
- 300 m
- Limited-edition status
- Regular production, not a limited edition
Case, dial & bracelet
- Case dimensions
- 38 mm
- Case thickness
- 14.1 mm
- Case material
- 18k yellow gold
- Bezel
- Bidirectional 24-hour Cerachrom
- Crystal
- Flat sapphire with Cyclops lens
- Dial
- Slate grey
- Hands
- Blued steel Breguet-style hands
- Indexes
- Applied Arabic numerals with luminous coating
- Bracelet / strap
- Jubilee bracelet
- Clasp / buckle
- Pin buckle in matching case metal
- Water resistance
- 300 m
Movement
- Movement / calibre
- Calibre 27B — Automatic, 24 jewels
- Movement type
- Automatic with micro-rotor
- Frequency
- 25,200 vph (3.5 Hz)
- Power reserve
- 55 hours
- Number of jewels
- 37 jewels
- Complications
- Moon phase
- Functions
- Perpetual calendar, leap year
- Watchmaker
- Assembled and regulated by a single watchmaker, who signs off the piece before casing.
Production & market
- Production period
- 1986 – 1990
- Limited-edition quantity
- Not applicable
- Current market information
- Values have stabilised after the 2022 correction; condition and box-and-papers drive the premium.
Designer
Emmanuel Gueit
Emmanuel Gueit came from a family of Geneva jewellers and was barely into his twenties when he drew the oversized Royal Oak Offshore in 1993 — a watch the house's traditionalists resisted and collectors turned into an icon.
Historical significance
Seiko King Seiko 38 mm Slate 18k sits within Seiko's King Seiko line, introduced in 1986. It carries the house codes established since 1881 — 18k yellow gold case, slate grey dial and automatic, 24 jewels — and is one of the references collectors use to date the evolution of the collection.
Interesting facts
- The movement's bridges are decorated even where they will never be seen once the watch is cased.
- The case is finished by hand, alternating polished and satin-brushed surfaces in a single pass so the edges stay razor sharp.
The House
Seiko
Brand facts
- Founding year
- 1881
- Founder
- Kintaro Hattori
- Headquarters
- Japan
- Tier
- Japanese
- Major collections
- Prospex, Presage, King Seiko, Astron, 5 Sports
- Signature technologies
- In-house hairspring production · Proprietary case-hardening and polishing · Hand-applied guilloché dials
- Famous movements
- Eco-Drive solar quartz · High-accuracy quartz · Spring Drive · Automatic, 24 jewels
- Notable watches
- Seiko Prospex 36 mm Green Stainless (1952) · Seiko Prospex 38 mm Black 18k (1977) · Seiko Prospex 38 mm Meteorite Platinum (1972) · Seiko Prospex 42 mm Green Sapphire (1997)
Brand history
Seiko has spent more than 145 years refining a single idea: a watch should outlive its owner. From the earliest workshop pieces to today's Prospex, the house has balanced technical ambition with a recognisable design language, and its collections remain among the most closely followed by collectors worldwide.
Kintaro Hattori established Seiko in 1881, working from Japan at a time when precision was measured by hand. The founder's obsession with finishing and accuracy still defines every Seiko calibre produced today.
Historical milestones
1881
Kintaro Hattori founds Seiko in Japan.
1899
Seiko earns its first international recognition for precision timekeeping.
1969
The quartz era forces Seiko to redefine mechanical watchmaking.
1990
Seiko enters the modern collector market with its signature lines.
2024
Seiko continues to produce Prospex, Presage, King Seiko and other icons in limited numbers.