Calibre 285 — smooth-rim balance in centre seconds

In brief

What the 268 did for the sub-seconds branch, the 285 did for centre seconds: the screwed balance gives way to a plain ring, while the 17 jewels and 18,000 vph stay exactly where they were.

Short history

In the centre-seconds branch this is the parallel to the balance change Omega introduced in the 268 — screwed rim out, smooth ring in. According to the firm's own technical guide of 1963, the calibre was renamed 286 shortly afterwards, once the next set of family improvements had been fitted.

Watches that used it

• Omega dress watches, late 1950s