In 1956, Rolex introduced one the most iconic watches ever made: the Day-Date. The Day-Date was the first waterproof self-winding chronometer certified wristwatch with a day and date function. And to top it off, it was only available in gold or platinum! Rolex also designed a new three-link bracelet, known as the ‘President,’ to pair with this special watch. With exception of the most modern executions, the Day-Date comes exclusively in a 36mm case.
REF. 65xx 66xx
The very first Day-Date references, the 6510 (with a domed bezel) and 6511 (with a fluted bezel) with the calibre 1055 movement, were produced for a single year before being fitted with an upgraded movement.
The next generation (references 6611, 6612, and 6613) contained an upgraded version of the cal. 1055 movement with a new balance wheel with microstella regulating screws. This upgrade yielded a certification from the Official Swiss Chronometer Testing Institute (COSC). While the previous Day-Dates featured the words “Officially Certified Chronometer” on the dial, these Day-Dates for the first time saw the famous “Superlative Chronometer Officially Certified” printing.