Omega started making calibre: 26.5 about 1927. It had a life span well into the late 1940’s. The movement was updated during it’s production run spawning many different variants. The Omega calibre 26.5 is essentially a miniature pocket watch movement that was suitable for the wrist.
Omega Calibre: 26.5
- Made approximately: 1927-1940’s
- Made in Switzerland
- Power reserve 37h
- 15 Jewels
- 18000 B/A
- DM 26.5mm
- H 3.95mm
Surface finish is not decorated, but has a very fine finish. Screws are polished and have a good finish. The bridges are rhodium plated.
Surface finish on top side of the plate and bridges: 8 Points
Surface finish on screws: 8 Points
Surface finish on crown and ratchet wheel: 6 Points
Movement Jeweling: 6 points
The movement has a pretty standard sub-seconds layout.
Movement design innovation (for ca 1927): 6 points
The Omega base plate has starburst finish. They sometimes come with perlage finish. Winding mechanisms are well made, but with a low finish on the screws. Gear train has a good finish. Setting the time and winding feels balanced.
Base plate finish: 7 Points
Setting and winding mechanism: 7 Points
Gear-train finish: 7 Points
Movement durability: 7 Points
Balance upgrades are common. Here is an example of early shock protection system. The last models had Inca shock.
Potential bonus points: 3
A bonus feature is the steel ratchet wheel washer that protects the balance bridge from wear.
Bonus points: 3
All variants of the calibre: 26.5 all had Breguet hairsprings and in good condition will keep good time.
Accuracy: 9 points
Power reserve of 37 hours is acceptable
Power reserve: 7 Points
Omega calibre: 26.5 points summary:
Surface finish on bridges and top side of base plate: 8
Surface finish top screws: 8
Surface finish on ratchet and ratchet wheel: 6
Movement Jeweling: 6
Movement innovative design for ca 1927: 6
Total bonus points: 3-6
Base plate finish: 7
Setting and winding mechanism: 7
Gear-train finish: 7
Movement durability: 7
Accuracy: 9
Power reserve: 7
Grand total: 81-84*
*With extra bonus points
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