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The Encyclopedia of Horology

Tokyo, Japan

Seiko

Verified

Integrated Japanese manufacture: clocks, mechanical watches, chronographs, quartz

History

Beginning as a clock and watch retailer and repairer, the firm became Japan's dominant manufacturer, producing pocket watches, railway watches, mechanical chronographs and, in 1969, the first commercially sold quartz wristwatch.

Major innovations

  • Series-production quartz wristwatch (Astron, 1969)
  • Automatic chronograph calibre 6139
  • Vertically integrated in-house component manufacture

Known markings

  • Case-back serial with year/month digits
  • Calibre number stamped on the movement or case back

Serial numbers

Seiko case serial numbers encode production year and month in a documented scheme, giving a decade-ambiguous but reliable month and year.

Collecting significance

The serial scheme makes Seiko unusually easy to date; dial and hand originality is the main authenticity question.

Photographs

Black Seiko watch close-up
Black Seiko watch close-up — gcardinal from Norway, CC BY 2.0. Wikimedia Commons file page
Dial detail of a Seiko Speed-Timer Chronograph Automatic 6138-0040 ("Bullhead"), 1976
Dial detail of a Seiko Speed-Timer Chronograph Automatic 6138-0040 ("Bullhead"), 1976 — Dnalor 01, CC BY-SA 3.0. Wikimedia Commons file page
Seiko SKX781 Orange Monster diver watch (2026-02-13)
Seiko SKX781 Orange Monster diver watch (2026-02-13) — Olgierd Rudak, CC BY-SA 4.0. Wikimedia Commons file page

Photographs are illustrative examples of the type, not necessarily the exact object described. Verify details against the source file page.

Sources & references

  1. Manufacturer service documentation
  2. Published Seiko dating references

Where sources disagree, the disagreement is stated rather than resolved silently.