Omega 861

Probable

Fitted to the Speedmaster Professional 145.022 and its successors. Jewel count varies across the production run — 17 jewels on earlier examples, 18 on later ones — so a count that differs from a published figure may simply date the movement. The exact year of the changeover to the rhodium-plated 1861 is reported as both 1996 and 1997 by different specialist sources and is tracked here as an open question.

Specifications

Movement manufacturer: Omega
Base caliber: Lemania 1873
Production: 1968–1996
Frequency: 21,600 vph (3 Hz)
Jewels: 17
Power reserve: 48 hours
Diameter: 27 mm
Winding: manual
Complications: Chronograph · Small seconds · 30-minute counter · 12-hour counter

Architecture

Manual-wind chronograph switched by a cam (shuttle) rather than a column wheel — a deliberate simplification for manufacturability and serviceability, not a cost failure.

Production revisions

c. 1996–1997Disputed
Replaced by the rhodium-plated 1861
The 861 was superseded by the 1861, whose principal difference is rhodium plating in place of the earlier copper-coloured finish. Specialist sources give the changeover as 1996 and as 1997; both are recorded and neither is asserted.

Service practice

Omega service commonly fitted 1861 parts into 861 movements as 861 stock was exhausted, producing mixed-plating movements that are genuine and correctly serviced. A movement showing both copper-coloured and rhodium-plated parts is a service history, not a red flag.

Open questions

OpenTransition dateHigh

Omega 861 to 1861 changeover year

In which year did Omega replace the calibre 861 with the rhodium-plated 1861 in Speedmaster Professional production?

Best current answer

Most likely 1996 or 1997. The catalog records the movement span as ending in 1996 and flags the transition as disputed rather than asserting either year.

Conflicting claims

Fratello's 145.022 buying guide places the change in 1996; other specialist accounts, including dealer catalogue descriptions, give 1997. No manufacturer statement establishing the date has been located. The transition was in any case gradual, since Omega continued fitting 861 parts from stock.

Scope Affects the production windows on every ReferenceMovementFit for the 145.022 and its successors.

Related calibers

Preceded by
Omega calibre 321
Succeeded by
Omega 1861
Built on
Lemania 1873

References using this caliber

Omega 145.022Factory
Speedmaster · ≤ 1996

Provenance of this record

Sources & Evidence

Secondary sourceSpecialist publication

Goldberger, John — Omega Speedmaster (Moonwatch Only)

Mondani Editore / La Sirène

Published: 2014-01-01

Cited for

This referenceHigh confidence

Secondary sourceCollector research

Ranfft Watch Movement Archive

Dr. Roland Ranfft (archived and maintained by volunteers)

Accessed: 2026-08-18