The Oyster Perpetual Day-Date 40 in 18 ct Everose gold, with an Eisenkiesel, diamond-set dial, diamond-set bezel and a President bracelet. Its dial features 10 baguette-cut diamonds. The Day-Date was the first watch to indicate the day of the week spelt out in full when it was first presented in 1956.MODEL CASE Oyster, 40 mm, Everose gold and diamonds OYSTER ARCHITECTURE Monobloc middle case, screw-down case back and winding crown DIAMETER 40 mm MATERIAL 18 ct Everose gold BEZEL Set with diamonds WINDING CROWN Screw-down, Twinlock double waterproofness system CRYSTAL Scratch-resistant sapphire, Cyclops lens over the date WATER RESISTANCE Waterproof to 100 metres / 330 feet MOVEMENT Perpetual, mechanical, self-winding CALIBRE 3255, Manufacture Rolex PRECISION -2/+2 sec/day, after casing FUNCTIONS Centre hour, minute and seconds hands Instantaneous day and date in apertures, unrestricted rapid-setting. Stop-seconds for precise time setting OSCILLATOR Paramagnetic blue Parachrom hairspring. High-performance Paraflex shock absorbers WINDING Bidirectional self-winding via Perpetual rotor POWER RESERVE Approximately 70 hours BRACELET President, semi-circular three-piece links BRACELET MATERIAL 18 ct Everose gold CLASP Concealed folding Crownclasp