Rolex 1055

The Rolex Caliber 1055 is a historically significant movement, purpose-built for the very first Rolex Day-Date (Ref. 6511) introduced in 1956. As part of Rolex’s 10xx series, it represented a major technological leap from the earlier “Bubbleback” calibers, featuring Rolex’s patented bi-directional “Perpetual” winding system with distinctive red anodized reversing wheels. Its defining feature was its complication: it was the first automatic, chronometer-certified wristwatch movement to display both the date and the day of the week spelled out in full in apertures on the dial. The Caliber 1055 is based on the robust Caliber 1030, but with the addition of the complex day and date mechanism. The movement operated at a traditional 18,000 A/h and was typically COSC certified, as noted by the “Officially Certified Chronometer” text on the dials of the watches it powered. The 1055 had a very short production run, lasting only until about 1959. Its day and date indicators changed slowly over several hours around midnight, a technical issue that Rolex addressed in its successor, the Caliber 1555, which introduced the iconic instantaneous change.