Calibre 866 — the first Moonwatch with a moonphase

In brief

In 1985 the Moonwatch gained a moonphase for the first time, and the 866 is the calibre that carried it. Hand-wound, 17 jewels, 21,600 vph, with the phase indicator at twelve and a date alongside.

Short history

Built on the Lemania 1883 ébauche, the 866 arrived in 1985 as the first Speedmaster with moon phases and stayed in production until 1988. Omega then replaced it with the calibre 1866: the same architecture, rhodium plating instead of the gilt finish — the same step up in finishing that separated the 861 from the 1861.

Watches that used it

• Speedmaster Professional Moonphase (1985–1988)