In Basel World 1984, Audemars Piguet launched the very first Royal Oak with perpetual calendar Model 5554, soon renamed 25554.

The reference 25554BA is an extremely rare reference. Produced between 1984 and 1992. The watchmakers had set themselves the objective of fitting Calibre 2120/2800, a 3.95 mm thick movement, into the same extra-thin case as the Royal Oak 5402. As a result, reference 2554 is only 7.5 mm thick, barely 0.4 mm thicker than the 5402. Considered the thinnest self-winding perpetual calendars made in a sporty case and the first complicated Royal Oak of its time, this model was an innovation in the industry of watchmaking, in an era devastated by the quartz crisis.

The Royal Oak Perpetual Calendar in yellow gold was by far the most important variant in terms of quantity, approximate total 270 units were made across all metals of which 223 units delivered in yellow gold, compared with 46 in steel and just one in platinum. This example is a pre leap-year indication ref. 25554 adorned with a rare black dial being both very aestitic and fragile but undeniably the most sought-after combination. Sotheby’s is honoured to offer such an important timepiece.