131 Audemars Piguet A very rare and incredibly attractive, Perpetual Calendar, moonphases wristwatch in platinum, with openworked dial, certificate of origin, VHS instruction manual, winding presentation box, reference 25636PT.

Estimate: € 150.000 –⁠ 300.000

Unveiled in 1986, just two years after Audemars Piguet introduced the first Royal Oak Perpetual Calendar, the reference 25636 was a technical and aesthetic revolution: the world’s first skeletonized perpetual calendar wristwatch with a sapphire caseback. Produced in just 312 pieces across all metals, only 34 examples were crafted in platinum. Bearing a D-series case number, the present 25636PT is a superb specimen of this early openworked generation, notable for its dial layout sans leap-year indication—a characteristic of the earliest perpetual calendars by Audemars Piguet, echoing the traditions of mid-century high horology. The white-printed sapphire dial provides an enthralling window into the intricate choreography of wheels and cams that define the perpetual calendar complication. Housed in platinum, a notoriously delicate and soft material, the case remains remarkably well-preserved, its sharp lines intact. Adding tremendous appeal is its extraordinary completeness: certificate of origin, presentation box with integrated winder, calendar inserts, hang tags, VHS manual, and more. A cornerstone in the history of the Royal Oak, this reference embodies the perfect confluence of avant-garde design, mechanical mastery, and rarity—rightly earning its place among the most coveted complicated Royal Oaks of the modern era.