Audemars Piguet Royal Oak Selfwinding Perpetual Calendar Ultra-Thin (World’s Thinnest QP)

The Audemars Piguet Royal Oak Selfwinding Perpetual Calendar Ultra-Thin, which started its life as a prototype watch named RD#2, is one of these watches that look so right. It is at once a superb design object and a highly engineered piece of horological ingenuity. Of course, it is the thinnest perpetual calendar wristwatch. But interestingly, its development was not initiated to break any record. The idea was simply to design a perpetual calendar Royal Oak that could easily slip under any cuff…

It is not a surprise to see Audemars Piguet presenting the thinnest perpetual calendar wristwatch. Ultra-thin watches and perpetual calendars are both parts of Audemars Piguet’s tradition. The brand claims to have presented the first perpetual wristwatch as early as 1955. The Royal Oak itself has been available with a perpetual calendar complication for some years, including the current versions. But Genta’s iconic design isn’t the most appropriate candidate for breaking a thinness record – in particular, when taking into consideration the need to respect the integrity of the Royal Oak’s design, with the elaborate geometry of its case, bezel and integrated bracelet.

When starting the development of the Audemars Piguet RD#2  Concept, the idea wasn’t to break any record but simply to design a Royal Oak perpetual calendar that could easily slip under a cuff and that would be perfectly adapted to modern active life. Most of today’s ultra-thin watches are developed with the goal of reducing the tolerances between their different components and shaving off crucial hundredths of a millimetre on the parts’ thickness. Hence, ultra-thin watches tend to be fragile.

However, Audemars Piguet used a different approach when designing the Royal Oak Selfwinding Perpetual Calendar Ultra-Thin, reengineering the perpetual calendar with functionality in mind. 

Giulio Papi (from APRP, a movement manufacture that forms part of Audemars Piguet) came up with the idea of reconstructing the three-level architecture of a perpetual calendar into a single-layer mechanism. The challenge was to integrate all functionalities into one layer. In particular, levers can cross each other when they are on different levels but this is no longer the case here. Two patents were filed for the development. The first one concerns the wheel related to the day of the month (at 6 o’clock below) that includes a notch to replace the end of the month cam. In relation with this day of the month wheel, the second patent is related to the 48-month mobile whose thickness can be reduced to the thickness of one wheel with a geometry using deep, curved grooves (at 4 o’clock below).

The clever perpetual calendar mechanism was built on top of the iconic extra-thin 2120 calibre. However, the calendar is not a module. It has been fully integrated into the movement to gain space. The dial itself acts as the upper bridge for the movement – which adds extra complexity when assembling the movement. The dial needs to be perfectly flat and is eventually adjusted by the watchmaker himself. The automatic calibre 5133 ends up at just 2.89mm. It operates at 19,800 vibrations per hour with a 40-hour power reserve. The movement is visible via the exhibition caseback with a monochrome white finish. It is decorated with Geneva stripes and fitted with an openwork rotor.

If poor legibility is often one of the shortcomings with perpetual calendars, in this instance it is excellent. This was integrated into the movement’s early development stage, maximizing space for the counters. This is the reason why the month and day-of-the-week counters are not on the centre axis for an optimal diameter. The day & night indicator was added to create a symmetrical counterpoint to the leap year indicator.

If the RD#2 Concept featured a “petite tapisserie” patterned dial, the Audemars Piguet Royal Oak Selfwinding Perpetual Calendar Ultra-Thin comes with a vertically satin-brushed blue dial. The new brushed dial might not be as iconic as the tapisserie pattern, but it aids legibility. The sub-dials are slightly recessed providing a sense of depth. The gold applied hour markers and hands feature luminescent coating. Although I would have preferred a more traditional execution, the moon phase is remarkable, featuring extreme detailing with a laser microstructured moon laid on a star-studded sky made of aventurine.

This impressive watch is 41mm in diameter but just 6.3mm in height. While the RD#2 was presented in platinum (and was really heavy on the wrist), the Royal Oak Selfwinding Perpetual Calendar Ultra-Thin is now manufactured in brushed titanium and polished platinum – the latter is used for the bezel and bracelet inter-links. This makes the watch much more wearable and comfortable. On the wrist, it feels just perfect. It is super comfortable while having a strong presence. And as you have come to expect from any Royal Oak watch, the finishing is top-notch with alternating brushed and polished surfaces. The way the light reflects off the watch is truly superb. The bracelet itself is in brushed titanium with polished platinum centre links. It is highly flexible and closed with a folding buckle.

The Audemars Piguet Royal Oak Selfwinding Perpetual Calendar Ultra-Thin reference 26586IP.OO.1240IP.01 retails for CHF 140,000. It certainly isn’t for every pocket but if you can afford it, this superb watch has everything it takes to get you to forget the price tag. Last, as for many Audemars Piguet watches, expect supply to be lower than demand…

For more information, please visit www.audemarspiguet.com.