Rolex Day-DateIn 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. 1803A new era dawned for the Day-Date when the earliest references (65xx & 66xx) were replaced by the 18xx series in 1959, which contained the cal. 1555 and later the cal. 1556 movement.The 18xx Day-Date was produced with a wide variety of dial colors and configurations. Characteristic for this era is the so-called ‘Pie-Pan’ dial that looks like an upside-down pie-pan (a concentric ring that slopes down from the flat centre).The last two digits of the 18xx references indicate the type of bezel or the bezel/case decoration: 1803 Fluted bezel