Calibre 261 — 17 jewels and an antimagnetic build

In brief

Two extra jewels and an antimagnetic build are what separate the 261 from the 260: 17 rather than 15, with the 18,000 vph that runs through the whole family. It was the first improvement Omega made to the 26x series after the 1949 renumbering.

Short history

The first round of improvements to the sub-seconds branch followed almost immediately on the renumbering of 1949: 15 jewels became 17, and resistance to magnetism was strengthened. Every other calibre in the 26x series would go the same way afterwards.

Watches that used it

• Omega dress watches, late 1940s