Audemars Piguet Royal Oak Offshore (26401PO.OO.A018CR.01)

Audemars Piguet - Jules Audemars Perpetual Calendar

While the slender elegance of the ultra-thin profile of this watch is truly fascinating, it is even more surprising when one considers that such a slim case houses a movement capable of indicating the day, the date, the month, the moon phases and the leap-year cycle thanks to a mechanism barely 4 mm thick! This exceptional timepiece appears to have captured the sparkling magic of the stars.

In 1978, Audemars Piguet launched the very first ultra-thin selfwinding perpetual claendar model. In 2008, the watchmakers in Le Brassus paid tribute to this creation with a 30th anniversary platinum limited edition. Today, the Perpetual Calendar selfwinding model is making its grand entrance into the Jules Audemars classic collection with an 18-carat pink gold case teamed with a choice of brown of silvered dial featuring a sunburst satin-brushed finish and refined pink gold hour-markers. The case has a particularly narrow bezel that highlights the time and the indications in the various counters and considerably facilitates read-off. With these two interpretations, the reinvented classical elegance of the Jules Audemars collection welcomes a new must-have model.

How can a timepiece, merely by the meshing of its toothed wheels, levers and clicks, successfully indicate the day, the date, the month, the moon phases and the leap-year cycle? The perpetual calendar system is an admirable mechanical reproduction of our calendar. The irregularity of the 30 or 31-day months is controlled by a cam - which is itself connected to a wheel - on which the various lengths of the month are defined. The protruding sections of around its circumference represent 31-day months, and the notches those of 30 days. On the same axis, a new wheel bearing a cam indicating standard months of February and a leap-year month of February performs one turn every four years and is thus able to keep accurate track of the leap-year cycle.

The brilliant perpetual calendar mechanism is teamed here with a selfwinding calibre that is a favourite among specialists: Calibre 2120. Measuring a mere 2.45 mm thick, it is quite simply the world's thinnest mechanical selfwinding movement with a central rotor: a paragon of fineness, reliability and performance entirely developed, produced and exquisitely finished within the Audemars Piguet workshops in Le Brassus.

The automatic winding is handled by a central rotor with a 21-carat gold segment. In addition to the sheer nobility of this metal, its weight also optimises bidirectional winding and thus the energy transmitted to the barrel - which in turn guarantees the power reserve. This effective winding system combined with the substantial power reserve ensures constant efficiency over a longer time period, and the quality of the winding also favourably influences the accuracy of the watch.

This same concern for performance led Audemars Piguet to choose a central rotor rather than an integrated mini-rotor. This particular technical solution means that the oscillating weight runs on another level than the barrel and the balance, thereby providing the latter two organs with more space in which to operate. The larger the barrel diameter, the greater the power reserve - which in this case amounts to 40 hours. Moreover, the larger balance diameter also enhances the precision of the watch.

The impeccable mirror-polished finish of the gear train and the use of 38 top-quality jewels enables optimal transmission of the force from the barrel to the escapement. The variable-inertia balance serves to ensure particularly fine adjustment and guarantees peerless accuracy.

The perpetual calendar mechanism is thus allied with an excellent base movement. The skill and mastery acquired by Audemars Piguet's watchmakers in the field of ultra-thin movements have enabled them to house the 355 parts of the Jules Audemars Perpetual Calendar within a tiny space just 4 mm thick.

The finishing and decoration of this movement are entirely on a par with this wealth of technical ingenuity. All the bridges are chamfered and polished by hand. Connoisseurs will take particular delight in the work on the internal and exterior angles. They will also be pleased to know that even the parts hidden from their view are the object of meticulous care. By way of example, not only is the upper part of the bridges adorned with a Côtes de Geneve motif, but the invisible lower part is also finely circular-grained. The mainplate features five different circular-graining diameters that create an exquisitely refined effect, while even the inside of the case-back is also circular-grained.