Hands On

The Oyster Perpetual Datejust

2021 February 17
By Washington

The Rolex Datejust is the archetype of the classic watch thanks to functions and aesthetics that never go out of fashion. Born in 1945, it was the first self-winding waterproof chronometer wristwatch to display the date in a window at 3 o’clock on the dial – hence its name. It consolidated all the major innovations that the brand had contributed to the modern wristwatch until then – chronometric precision (first chronometer certificates granted to a Rolex wristwatch as of 1910), waterproofness (creation of the Oyster case in 1926) and the self-winding mechanism (Perpetual rotor patented in 1931).


The Datejust revolutionized wristwatch date display. Traditionally, the date was indicated by a hand pointing to markings around the edge of the dial. With the Datejust, Rolex introduced a calendar that displayed the date via a disc in a window at 3 o’clock. This would become the watchmaking standard. In 1953, the Cyclops lens was added to the crystal, magnifying the date for easy reading. In 1956, the date change became instantaneous. The Datejust is also equipped with a mechanism allowing rapid adjustment of the date using the winding crown.


The Datejust has spanned eras while retaining the enduring aesthetic codes that make it so instantly recognizable. These include the characteristic shape of its Oyster case, the 18 ct gold fluted bezel, the Cyclops lens over the date and the five-piece link Jubilee bracelet, which has become a classic – particularly in the yellow Rolesor version, combining links in steel and 18 ct yellow gold.


Like all Rolex watches, the Datejust is certified as a Superlative Chronometer. This exclusive designation testifies that every watch leaving the brand’s workshops has successfully undergone a series of tests conducted by Rolex in its own laboratories and according to its own criteria, which exceed watchmaking norms and standards. These tests are carried out on the fully assembled watch, in order to guarantee superlative performance on the wrist. 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. The precision of every movement – officially certified as a chronometer by COSC (Swiss Official Chronometer Testing Institute) – is tested a second time by Rolex after being cased, to ensure that Oyster Perpetual  it meets criteria for precision that are far more exacting than those for an official chronometer. The tolerance for the average rate of a Rolex Superlative Chronometer is of the order of −2/+2 seconds per day. Its precision is tested by Rolex using an exclusive methodology that simulates the conditions in which a watch is actually worn and is much more representative of real-life experience. The Superlative Chronometer certification testing is carried out after casing using state-of-the-art equipment specially developed by Rolex. The entirely automated series of tests also checks the waterproofness, the self-winding capacity and the power reserve of 100 per cent of Rolex watches. These tests systematically complement the qualification testing during development and production that ensures the watches’ reliability, robustness, and resistance to magnetic fields and shocks.


The Datejust’s Oyster case, guaranteed waterproof to a depth of 100 metres (330 feet), is a paragon of robustness and elegance. The characteristically shaped middle case is crafted from a solid block of particularly corrosion-resistant Oystersteel or 18 ct gold. The case back, edged with fine fluting, is hermetically screwed down with a special tool that grants only certified Rolex watchmakers access to the movement. The winding crown, fitted with the Twinlock double waterproofness system, screws down securely against the case. The bezel can be smooth, domed, fluted or set with diamonds. The crystal, with a Cyclops lens at 3 o’clock for easy reading of the date, is made of virtually scratchproof sapphire. The waterproof case provides the Datejust’s high-precision movement with optimal protection.


Datejust models are equipped with calibre 2235 or 2236 (Datejust 31), or calibre 3235 (Datejust 36 and Datejust 41), self-winding mechanical movements entirely developed and manufactured by Rolex. The architecture, manufacturing and innovative features of these movements make them exceptionally precise and reliable. The oscillator has a large balance wheel with variable inertia regulated extremely precisely via gold Microstella nuts. It is held firmly in place by a height-adjustable traversing bridge enabling very stable positioning to increase shock resistance. Calibre 3235 features an optimized version of the blue Parachrom hairspring, manufactured by Rolex in an exclusive paramagnetic alloy, whilst calibre 2236 incorporates a Syloxi hairspring in silicon, Oyster Perpetual which is patented and manufactured by the brand. Both hairsprings are insensitive to magnetic fields, offer great stability in the face of temperature variations and remain up to 10 times more precise than a traditional hairspring in case of shocks. In calibres 2235 and 3235, the hairspring is fitted with a Rolex overcoil, guaranteeing its regularity in any position. The geometry of the Syloxi hairspring found in calibre 2236 offers the same level of performance. Calibres 2235, 2236 and 3235 are fitted with a self-winding module featuring a Perpetual rotor, which ensures continuous winding of the mainspring by harnessing the movements of the wrist to provide a constant source of energy. The Datejust’s movements will be seen only by certified Rolex watchmakers, yet they are beautifully finished and decorated in keeping with the brand’s uncompromising quality standards.


Calibre 2236 and calibre 3235 are new-generation movements entirely developed and manufactured by Rolex for a superlative level of performance. Consummate demonstrations of Rolex technology, they offer fundamental gains in terms of precision, power reserve, resistance to shocks and magnetic fields, convenience and reliability. The oscillator is fitted on high-performance Paraflex shock absorbers, designed and patented by Rolex, which increase the movement’s shock resistance. Calibre 2236 features a paramagnetic nickel-phosphorus escape wheel and has a power reserve of approximately 55 hours. Calibre 3235 incorporates the Chronergy escapement, patented by Rolex, which combines high energy efficiency with great dependability. Made of nickel-phosphorus, this escapement is also insensitive to magnetic fields. Thanks to the barrel architecture and the escapement’s superior efficiency, the power reserve of calibre 3235 extends to approximately 70 hours.