Omega Caliber 2500A: The First Mass-Market Co-Axial Movement

The Omega Caliber 2500A is a milestone in modern horology. Launched in 1999, it was the first commercial movement to feature the Co-Axial escapement, a revolutionary technology developed by the legendary English watchmaker George Daniels. The 2500A marked Omega’s bold step into the future by attempting to mass-produce a mechanical movement with reduced friction, longer service intervals, and greater long-term accuracy.

Built upon the solid foundation of the ETA 2892-A2, the 2500A wasn’t a full in-house caliber—but it was extensively re-engineered to house Daniels’ unique escapement. It was the first time this system was available to the general public, making it a significant historical achievement not just for Omega, but for modern watchmaking as a whole.

Technical Specifications

• Type: Automatic

• Base Caliber: ETA 2892-A2

• Jewels: 27

• Diameter: 25.6 mm

• Height: Approx. 3.6 mm

• Frequency: 28,800 A/h (4 Hz)

• Power Reserve: ~48 hours

• Functions: Hours, minutes, central seconds, date

• Escapement: Co-Axial (1st generation)

• Chronometer Certified: Yes (COSC)

• Finish: Rhodium-plated, Geneva stripes, Omega logo on rotor

The Co-Axial Concept in Practice

George Daniels’ Co-Axial escapement sought to eliminate sliding friction between the pallet fork and escape wheel—a limitation in traditional Swiss lever escapements. His design introduced a three-level escapement where the impulse was delivered with a pushing (rather than sliding) motion. This significantly reduced the need for lubrication and allowed for longer service intervals and more consistent timekeeping over time.

The Caliber 2500A was the first test of bringing this theory into mass-market reality. Omega took the proven ETA 2892-A2 and made structural modifications to accommodate the new escapement without changing the movement’s base frequency or architecture.

Strengths and Challenges

The 2500A was a bold experiment—and for the most part, a success. It proved that the Co-Axial escapement could work in an industrially scaled wristwatch. Early adopters benefited from:

• Reduced friction and wear

• Extended service intervals

• Solid chronometer-grade accuracy

• High efficiency in a slim automatic movement

However, the 2500A also revealed that scaling the Co-Axial escapement had limitations. The escapement was originally designed to operate best at lower frequencies (around 21,600 A/h), but Omega retained the ETA’s 28,800 A/h beat rate. This mismatch introduced reliability issues over time, particularly with lubrication and wear on the escapement components.

Omega responded to these issues by refining the movement over multiple versions—leading to the 2500B, 2500C, and 2500D—each introducing technical corrections to improve performance.

Watches Powered by the 2500A

The Caliber 2500A was used in early Omega De Ville Co-Axial Chronometers—conservatively styled dress watches designed to emphasize Omega’s horological innovation rather than sportiness. These models featured:

• Simple, clean dials with date windows

• Applied markers and dauphine hands

• Modest 36–38mm case sizes

• Transparent casebacks showcasing the movement

Some early Aqua Terra models also used the 2500A, though most later transitioned to improved versions of the caliber.

Collector Insight

The Caliber 2500A holds special value as the origin point of Omega’s modern Co-Axial strategy. Although later revisions were mechanically superior, the 2500A remains:

• Historically significant as the first mass-produced Co-Axial

• Collectible for Omega enthusiasts and George Daniels admirers

• Less common, due to its limited production run and eventual replacement

Collectors should look for well-serviced examples, as some early 2500A watches may have required escapement upgrades or part replacements.

Final Thoughts

The Omega Caliber 2500A wasn’t perfect—but it was revolutionary. As the first Co-Axial movement offered to consumers, it laid the groundwork for what would become Omega’s defining mechanical identity. For those who appreciate innovation, legacy, and mechanical experimentation, the 2500A is a fascinating piece of horological history ticking quietly under the radar.