The Oyster Perpetual Lady-Datejust is an icon in the world of watches. It was introduced in 1957, at a time where women were changing — they were enjoying new, active lifestyles. They found a new sense of autonomy, and wanted to control their own destinies and manage their time more precisely. Hans Wilsdorf, founder of Rolex, understood what the modern woman wanted, and so was born the Lady-Datejust.
Pioneering women have always been a keystone in the history of Rolex. Since the earliest days of the brand, they have inspired the creation and development of special timepieces that would support their quest for empowerment. The Lady-Datejust is a celebration of those who dare to lead the way. It embodies precision while combining classic elegance and technical performance.
Designed for the slender wrists of women, the Lady-Datejust features a 28 mm Oyster case, guaranteed waterproof to a depth of 100 metres (330 feet), and crafted from Oystersteel or 18 ct gold. Its sapphire crystal is virtually scratchproof, with a Cyclops lens at 3 o’clock over the date. Multiple dial variations are available, in a wealth of materials, colours, markers and motifs, providing the discerning woman with options to customise her watch and make her statement.
Landmark in Watchmaking
Hans Wilsdorf once stated of his enduring mission: “Ladies want the best of both worlds: a tiny watch and an accurate movement. Yet, the smaller the watch, the more difficult it is to make it accurate.”
This is precisely why the Lady-Datejust was ‘inspired by audacity’, as it was a major technical challenge to produce such small precise movements in the 20th century. Since its inception, Rolex has made various improvements to the heart of the Lady-Datejust. Presently, it is equipped with calibre 2236, a self-winding mechanical movement entirely developed and manufactured by Rolex.
Calibre 2236
Introduced in 2014 calibre 2236 is a self-winding mechanical movement entirely developed and manufactured by Rolex, offering outstanding performance in terms of precision, power reserve, resistance to shocks and magnetic fields, convenience and reliability. A consummate demonstration of technology, this movement carries a number of patents. Let’s delve deeper into this movement which is at the forefront of watchmaking technology.
The heart of the Lady-Datejust
Those with a passion for watches know that in mechanical watches, the oscillator is the ‘guardian of time’, maintaining the precision of the watch through the interactions of the balance wheel and the hairspring.
The oscillator of calibre 2236 has a balance wheel with variable inertia regulated extremely precisely via gold Microstella nuts, held firmly in place by a height-adjustable traversing bridge enabling very stable positioning to increase shock resistance. The oscillator is also fitted on high-performance Paraflex shock absorbers, designed and patented by Rolex.
The hairspring of a movement is a delicate component that is subject to environmental disturbances that can adversely affect the oscillator’s performance. Magnetic fields, temperature variances and shocks all serve to throw the oscillator off.
To provide greater stability in the face of these disturbances, Rolex developed the new Syloxi hairspring, adding a second distinct paramagnetic balance spring technology to complete its range of high-performing hairsprings, alongside the blue Parachrom hairspring.
The Syloxi hairspring is entirely manufactured in-house by Rolex from a silicon and silicon oxide composite, a combination of materials whose thermo-compensating and paramagnetic properties allow the hairspring to maintain its high precision when subjected to temperature fluctuations and magnetic interference.
Utilising deep reactive ion etching technology (DRIE), the hairspring is crafted with a patented geometry that optimises its isochronism and thus the regularity of the oscillations of the balance wheel-hairspring assembly. The variable pitch and thickness of the coils, optimised along the whole length of the hairspring, ensures constant development in all positions, compensating for the effects of gravity.
Examining the Syloxi would show a hairspring fixed to the balance staff and bridge using a patented flexible collet, eliminating the need for glue and keeping the hairspring’s inner end perfectly perpendicular, flat and self-centring.
Looking along the hairspring, one can see that the Syloxi terminates in a more rigid, reinforced crescent-shaped part that allows a two-point fixation to the traversing balance bridge, ensuring that the hairspring is perfectly centred, perfectly flat and free of any residual mechanical stress in its active zone.
Fixing it this way allowed Rolex to optimise the beat adjustment using a Paraflex shock absorber that features a fluting for this purpose, which is also the signature of Syloxi-equipped calibres.
This marvel of precision engineering provides the Syloxi with great stability in the face of temperature variations; up to 10 times more precision than a traditional hairspring in case of shocks; and higher resistance to magnetic fields.
Also of interest is that the calibre 2236 is equipped with a paramagnetic nickel-phosphorus escape wheel enhancing its resistance to magnetic fields.
Like all Rolex watches, the Lady-Datejust is covered by the Superlative Chronometer certification redefined by Rolex in 2015. The precision of a Rolex Superlative Chronometer is of the order of −2/+2 seconds per day — the rate deviation tolerated by the brand for a finished watch is significantly smaller than that accepted by COSC for official certification of the movement alone.
Each calibre 2236 is fitted with a self-winding module via a Perpetual rotor, which ensures continuous winding of the mainspring by harnessing the movements of the wrist to provide constant energy. This offers a power reserve of approximately 55 hours.
As with all Rolex movements, calibre 2236 is made in-house by Rolex, including all components.
A timepiece that encapsulates Rolex values, the emblematic Lady-Datejust has been a byword for style and technical performance ever since its launch, celebrating those who dare to lead the way.
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