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. Several variants where made during it’s production run:
26.5 : bimet. balance
26.5T1: bimet. balance
26.5T2: bimet. balance
26.5T2 PC: bimet. balance, Incabloc
26.5T3: monomet. balance
26.5T3 PC: monomet. balance, Incabloc
26.5T3 PC AM: monomet. balance, antimagnetic, Incabloc
100: =26.5T3 PC AM since 1949
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: 2
All variants of the calibre: 26.5 all had Breguet hairsprings and in good condition will keep good time.
Accuracy: 8 points
Power reserve of 37 hours is acceptable
Power reserve: 6 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: 2-5*
Base plate finish: 7
Setting and winding mechanism: 7
Gear-train finish: 7
Movement durability: 7
Accuracy: 8
Power reserve: 6
Grand total: 78-81*
*Inca shock.