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 the exception of the modern ‘Day-Date II’, the Day-Date comes exclusively in a 36 mm case.Reference 18xxxThe arrival of the 18xxx series Day-Dates in 1978 ushered in the first signs of the ‘modern’ watchmaking era for Rolex. These Day-Dates were the first regular production Rolex watches to receive a sturdy and scratch resistant sapphire crystal. To accommodate the new crystal, the iconic Oyster case had to be increased in thickness as well, giving the Day-Date a more modern look.Other significant developments were the change from the beloved pie-pan dials to the new flat dials and the unveiling of a brand new movement. The caliber 3055 introduced a single quickset function, which meant that the date could finally be adjusted separately from the time and date.