Known as the “presidents’ watch”, the Oyster Perpetual Day-Date is celebrating its 60th anniversary in 2016. To mark this special occasion, it has been given a bright new dial in green, Rolex’s hallmark colour. The Oyster case of the Day-Date, guaranteed waterproof to a depth of 100 metres (330 feet), is a paragon of robustness, proportion and elegance. The characteristically shaped middle case is crafted from a solid block of 18 ct polished gold. The fluted case back is hermetically screwed down with a special tool that allows only Rolex watchmakers to access the movement. Fitted with the Twinlock double waterproofness system, the winding crown screws down securely against the case. The crystal, with a Cyclops lens at 3 o’clock for easy reading of the date, is made of virtually scratch proof sapphire. The waterproof case provides optimum protection for the Day-Date 40’s high-precision movement. The Day-Date 40 is equipped with a new-generation movement, calibre 3255, entirely developed and manufactured by Rolex for a superlative level of performance. This self-winding mechanical movement is at the forefront of the watchmaking art. A consummate demonstration of Rolex technology with 14 patents, it offers fundamental gains in terms of precision, power reserve, resistance to shocks and magnetic fields, ease of use and reliability. The Day-Date 40 is covered by the Superlative Chronometer certification redefined by Rolex in 2015. This exclusive designation testifies that the watch has successfully undergone a series of tests conducted by Rolex in its own laboratories according to its own criteria, which exceed watchmaking norms and standards. The certification applies to the fully assembled watch, after casing the movement, guaranteeing superlative performance on the wrist in terms of precision, power reserve, waterproofness and self-winding. The precision of a Rolex Superlative Chronometer after casing is of the order of -2/+2 seconds per day, or more than twice that required of an official chronometer. The Superlative Chronometer status is symbolized by the green seal that comes with every Rolex watch and is coupled with an international five-year guarantee.