Audemars Piguet Quantieme Perpetuel Automatique 25668 25668

This heading covers Audemars Piguet's vintage automatic perpetual calendars, starting with ref. 5548 of 1978. At its launch it was among the thinnest self-winding perpetual calendars made, and it helped revive interest in mechanical complications at a time when quartz dominated.

The watches use caliber 2120/2800, an ultra-thin automatic base with a perpetual calendar module, and show day, date, month, moon phase and leap year in a round, classic case. Later references in the catalog, such as the 25548, 25558, 25657 and 25661, followed in the 1980s and 1990s. Dealers check that the calendar advances correctly, that the dial is original and whether the watch has been serviced by the brand.