Model caseModel caseOyster, 36 mm, yellow goldOyster architectureMonobloc middle case, screw-down case back and winding crownDiameter36 mmMaterial18 ct yellow goldBezelFlutedWinding crownScrew-down, Twinlock double waterproofness systemCrystalScratch-resistant sapphire, Cyclops lens (2.5x) over the dateWater-resistanceWaterproof to 100 metres / 330 feetMovementMovementPerpetual, mechanical, self-windingCalibre3155, Manufacture RolexFunctionsCentre hour, minute and seconds hands. Instantaneous date and day in windows on the dial with rapid setting. Stop seconds for precise time settingPrecisionOfficially certified Swiss chronometer (COSC)OscillatorParamagnetic blue Parachrom hairspringWindingBidirectional self-winding via Perpetual rotorBraceletBraceletPresident, semi-circular three-piece linksBracelet material18 ct yellow goldClaspConcealed folding CrownclaspDialDialBlack set with diamonds and rubiesGem-settingDiamonds in 18 ct gold settings and baguette-cut rubies at 6 and 9 oclockFrom its launch in 1956, the Day-Date was immediately recognized as the watch worn by influential people. The Day-Date was the first calendar wristwatch to display the day, as well as the date, in its entirety. Faithful to its noble origins, the Day-Date is made exclusively of gold or platinum, the most precious metals.