Firstlaunched in 1978, theQuantime Perpetuelby Audemars Piguet was the worlds thinnest automatic perpetual calendar.The reference 5548 was was the first reference of this newly released perpetual calendar, birthing a category of watches which has taken on many different forms.

The Quantime Perptuel

In the late 70s, complicated wristwatches were exceedingly rare. The Quartz Crisis had decimated the watchmaking industry, with the number of watchmakers in Switzerland having dropped from 1,600 to 600.Against all odds, three watchmakers at Audemars Piguet decided to develop the worlds thinnest automatic perpetual calendar movement. The project was , with the manufactures upper management completely unaware of what was going on. The watchmakers worked in their free time, often meeting at night to discuss their work.

In 1977, they surprised George Golay, the CEO of Audemars Piguet at the time, with the finished calibre. A risk taker whod already released the Royal Oak a few years prior, Golay was confident that the manufacture could successfully commercialise the automatic perpetual calendar. When it was launched in 1978, the Quantime Perpetuelwas the worlds thinnest automatic perpetual calendar. To put things in perspective, in 1984, only 1,066 perpetual calendars were produced in Switzerland. Of those, Audemars Piguet made 675.

Though the Royal Oak often gets credit for helping Audemars Piguet survive in the wake of the Quartz Crisis, evidence suggests the Quantime Perpetuel played a much greater role. According to the manufacture, 7,219 perpetual calendars were made over a fifteen year period, including some which were integrated into . A canvas to experiment with , 70 different models were produced, with around 200 variations documented.

A ClassicDesign

The early reference 5548 is distinguished by the small Swiss signature at the bottom of the dial rather than the later Swiss Made, signalling that this watch is part of the earliest watches to leave the manufacture. Sources note that total production was documented at 2183 pieces, and of those, yellow gold cases were the most widely produced.

The lines of the Quantime Perpetuel were pennedby Jacqueline Dimier, whois considered by some as the protg of the legendary. The perpetual calendar indications are laid out in an intuitive manner. The date and day are shown at three and nine oclock respectively, with the months displayed at twelve oclock. A moonphase indication is placed at six oclock, with graduations for the moon position just above. The Audemars Piguet font is flat and restrained, imbuing this piece with a certain vintage appeal. Later versions of the same reference are known to have a more contemporary font, giving them a distinctively more modern appearance.

As this is one of the earlier examples, the sub-dials are not recessed, enclosed between two thin black strokes, with the 6 oclock sub-dial in a semi-circle. Meanwhile, the gold stick hands provide excellent legibility against the white background.The case is a double-stepped bezel, with three pushers only very visible when the watch is turned over. At 36mm in diameter and less than 8mm thick, this5548BA sits comfortably on the wrist. On the reverse of theyellow gold case, the watch features finely-engraved markings, confirming the watchs individual case number.

The Movement

The reference 5548 is the first watch to be fitted with the ultra-thin, automatic calibre 2120/2800, derived from Jaeger-LeCoultres legendary. The Caliber 2120 was an initial project of Jaeger LeCoultre in 1967, funded and contributed by Audemars Piguet, and famous for its adoption by Audemars Piguet, Patek Philippe and Vacheron Constantin.

The ultra-thin automatic 2120/2 calibre features 38 working jewels, a Gyromax balance and four ruby wheels to support the full-diameter rotor, which runs on a beryllium rail for stability. The rotor is decorated with Geneva stripes and edged with 21-carat gold, to increase the oscillating mass. The movement remains the thinnest full-rotor self-winding movement in the world, considered by many as one of the most technically refined wrist-watch movements ever made.

The Set

The watch is accompanied by its original outer and inner box, a service booklet, a Quantime Perpetual Manual, a Certificate of Origin and an Extract from the Archives. The set also includes a setting pin and servicing paperwork, an original Audemars Piguet black alligator strap and the corresponding yellow gold tang buckle.

Closer look