Omega calibre: 26.5

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 has a very fine finish with nicely cut bridges with beveled edges. 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: 8 Points

A nice feature is the steel ratchet wheel washer that protects the balance bridge from wear. This helps the movement durability.  

Balance upgrades are common. Here is an example of early shock protection system. The last models had Inca shock.

Potential modernisation bonus points: 3*

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: 3*

Base plate finish: 7

Setting and winding mechanism: 7 

Gear-train finish: 7

Movement durability: 8

Accuracy: 8

Power reserve: 6

Grand total: 77-80*

*Inca shock.