Calibre 331 — antimagnetic bumper chronometer

In brief

Two changes separate the 331 from the 330: it is built to resist magnetism, and it is regulated to chronometer standard. Jewelling, beat rate and diameter stay exactly where they were, at 17 jewels, 19,800 vph and 30.1 mm.

Short history

By 1947 Omega had several years of bumper production behind it, and the 331 carries the improvements the brand was introducing across the whole family: resistance to magnetic fields, and the accuracy expected of a chronometer.

Watches that used it

• Omega automatic watches of the 1940s