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Omega 2500

Probable

The first series-produced Co-Axial caliber, and the movement in the Seamaster and Planet Ocean through the 2000s. It exists in successive internal revisions — designated A, B, C and D in collector usage — of which the later ones changed the beat rate and addressed early service issues. Those revision letters are not consistently marked on the movement, which is why an examiner should describe what the movement IS rather than assert which revision it is.

Specifications

Movement manufacturer
Omega
Base caliber
ETA 2892-A2
Production
1999–2012
Frequency
25,200 vph (3.50 Hz)
Jewels
27
Power reserve
48 hours
Winding
automatic
Complications
Centre seconds · Date
Certification
COSC chronometer

Architecture

The 1120 architecture — an ETA 2892-A2 base — rebuilt around George Daniels's Co-Axial escapement. Automatic, centre seconds, quickset date, chronometer-certified.

Service practice

Early 2500s were revised in service, and a watch of the period may legitimately carry a later revision than it left with. That is a manufacturer service action and is not a finding against the watch; it does mean the movement's characteristics may not match the reference's original specification, and the discrepancy should be recorded as service history rather than as a mismatch.

Open questions

OpenTransition dateHigh

Dating the Co-Axial 2500 revisions

When did each internal revision of the caliber 2500 enter production, and can a revision be identified from the movement without reference to Omega's service records?

Best current answer

Collector research distinguishes the revisions by beat rate and escapement detail and orders them A, B, C, D. The letters are collector usage; they are not consistently marked on the movement, and Omega has published no revision-to-date table.

Scope Consequential because early 2500s were revised under service, so a watch may legitimately carry a later revision than it shipped with. Without a revision-to-date mapping the catalog cannot state which revision a reference should carry, and an examiner should describe the movement rather than assert its revision.

Related calibers

References using this caliber

Provenance of this record

Sources & Evidence

Primary sourceManufacturer documentation

OMEGA — Calibres and Master Chronometer certification

OMEGA SA

Accessed
2026-08-18

Cited for

This referenceHigh confidence
View source ↗
Secondary sourceCollector research

Omega collector research on reference numbering and caliber revisions

Omega Forums and allied collector communities

Accessed
2026-08-18

Cited for

This referenceProbable

Collector research distinguishes 2500A/B/C/D by beat rate and escapement detail; Omega has not published a revision-to-date table.

View source ↗

Last verified: Not yet reviewed