In 1978, Audemars Piguet caused a sensation by introducing the first ultra-thin selfwinding perpetual calendar. The watchmakers in Le Brassus are now paying tribute to this creation with a special anniversary limited edition of 90. The barely 4 mm thick movement of the Jules Audemars 30^th Anniversary Perpetual Calendar represents a spectacular feat of miniaturisation.

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 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 months are defined. 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 take the leap-year cycle into account. This means that the Jules Audemars 30^th Anniversary Perpetual Calendar will require no correction before March 1^st 2100. All that will be required on this date is to actuate the correctors positioned on the side of the case, and the mechanism will be fully readjusted for another century.

The broad bezel diameter facilitates reading off the time as well as the various calendar subdials. The latter are surrounded by a polished decorated fillet that highlights their snailed décor making a pleasing contrast with the satin-brushed finish of the dial.

However, its radiance is essentially due to the Tuscany shade of blue specially selected for this occasion and which is unmistakably reminiscent of the skies graced with angelic figures as depicted in the works of 15^th century Florentine painters. Combined with the noble platinum case and white gold hands and hour-markers, it vividly expresses the fresh take on classicism embodied in the Jules Audemars 30^th Anniversary Perpetual Calendar.

Reference	:	26000PT.OO.D028CR.01 Limited series of 90
Movement	:	Calibre: 2120/2802, ultra-thin, selfwinding Total diameter: 12? lignes (28.4 mm) Casing-diameter: 28 mm Thickness: 4 mm 38 jewels 355 parts Power reserve: up to 40 hours Cadence of the balance: 19,800 vibrations per hour Finishing: all movement parts bevelled, adorned with a “côtes de Genève” motif and circular-grained
Case	:	950 platinum Diameter: 41 mm Thickness: 9.15 mm Sapphire crystal caseback Water-resistance: 20 m
Dial	:	Tuscany blue dial with white gold applied hour-markers White gold hour and minute hands
Strap	:	“Large square-scale” hand-sewn alligator leather with platinum AP folding clasp
Functions	:	Hours and minutes Day Date Month Leap-year indication Moon phases