Omega calibre 321
High confidenceThe caliber in the Speedmaster references worn during the Apollo programme, and the reason pre-1969 Speedmasters command the premium they do. Omega reintroduced a reconstructed 321 in 2019; a modern 321 is therefore not evidence of a vintage watch, and the two must not be conflated.
Specifications
- Movement manufacturer
- Omega
- Base caliber
- Lemania 2310 (CH 27 C12)
- Production
- 1949–1968
- Frequency
- 18,000 vph (2.50 Hz)
- Jewels
- 17
- Power reserve
- 44 hours
- Diameter
- 27 mm
- Winding
- manual
- Complications
- Chronograph · Small seconds · 30-minute counter · 12-hour counter
Architecture
Manual-wind column-wheel chronograph with a lateral clutch, developed with Lemania. The column wheel is visible through the caseback aperture on modern re-editions and is the feature most often cited in distinguishing it from its successor.
Authentication notes
- BridgesHigh confidence
Column wheel versus cam: the 321/861 distinction
The 321 switches the chronograph with a column wheel; the 861 that replaced it uses a cam (shuttle). This is the primary means of telling the two apart with the caseback off, and it is decisive for dating. It is not, by itself, an authenticity finding — a service movement swap produces exactly this mismatch legitimately.
Service practice
Omega service in the 1970s and 1980s sometimes replaced a 321 with an 861 outright. A 321-era Speedmaster carrying an 861 is a documented service outcome — an originality and valuation matter, and not evidence that the watch is not what it claims.
Related calibers
Succeeded by
Omega 861Built on
Lemania 2310
References using this caliber
No catalog references are linked to this caliber yet.
Provenance of this record
Sources & Evidence
Goldberger, John — Omega Speedmaster (Moonwatch Only)
Mondani Editore / La Sirène
- Published
- 2014-01-01
Cited for
OMEGA Vintage Database
OMEGA SA
- Accessed
- 2026-08-18
Cited for
Last verified: Not yet reviewed