Omega 503

The Omega Caliber 503 is a historically important movement from the mid-1950s, as it was part of Omega’s first series of full-rotor automatic movements (the 50x family) that replaced the earlier “bumper” automatics. Introduced in 1955, this chronometer-grade caliber was technologically advanced for its time, featuring not only a date complication in a window but also a distinct 24-hour indicator sub-dial, which served as a day/night display. This combination of features was reserved for high-end models like the Globemaster, Seamaster Calendar, and early Constellations. The Caliber 503 represents a key transitional moment for Omega, combining the newfound efficiency of a 360-degree rotor with useful complications, paving the way for the legendary 55x/56x series that would follow.