25668BA Audemars Piguet Perpetual Calendar Skeleton

This is the ref. 25668BA, the ultimate evolution of the original 5548, produced from 1988 until 1993 to celebrate the resurgence of complicated mechanical watchmaking to Switzerland. In yellow gold, just 94 examples of the ref. were made. It is one of the most highly collected, highly finished QPs of its time.

At launch in 1978, the Quantième Perpétuel was the thinnest perpetual calendar that had ever been made at 3.95mm. Its calibre 2120/2800 was developed in the throes of the quartz crisis in secret, by a team of three senior watchmakers (lead watchmaker Michel Rochat, founder of the technical department Daniel Golay, and head of service Wilfred Berney) who feared AP’s budget would not allow for the development of complicated mechanical watchmaking. The three formed their own skunkworks and worked after-hours in secret unpaid. The calibre utilizes thoroughly reworked JLC 920 ébauche with its own calendar works. The result revived not just Audemars Piguet's complications, but all of Switzerland. Calibre 2120/2800 changed the course of watchmaking history. The 36mm case was then penned by Jacqueline Dimier, arguably her most famous work with its gracefully downturned lug and steeped bezel. 

The 25668BA was available in gold and silver subdials, where yellow is the more produced. But it is between the subdials where effort has been poured. First, the sword subdial hands are heat blued. The openworking encompasses hand engraving, bevelling, anglage, black polish, and an uncountable number of inner angles. The skeletonized moonphase is a particularly thoughtful touch. It is a celebration of traditional technique flourishing again in Switzerland. 

The 25668 is one of the most visually captivating of the Holy Trinity post-quartz perpetual calendars. To the extent that modern AP has become the Royal Oak company, they do immense disservice to this legacy, one of the greatest in watchmaking. This watch led the charge for mechanical watchmaking’s return against the growing quartz shadow and sold to great success. It is easily one of the most critical, significant references of the last century.

This example has a great case, with a decent amount of wear. It's probably seen a light polish and not much more. The lugs are still lovely and full. It comes with some original paperwork but not a complete set from a well-regarded London retailer.