The Audemars Piguet Royal Oak Perpetual Calendar Openworked, reference 25636BA, stands as one of the most coveted and technically accomplished Royal Oak models ever produced. Introduced in the late 1980s, this ultra-thin perpetual calendar combines the architectural brilliance of the Royal Oak with the mechanical mastery of openworked watchmaking—all housed in an 18k yellow gold case.
“Openworked,” or skeletonization, refers to revealing the movement through the dial and caseback, showcasing the watch’s intricate mechanics. Audemars Piguet spends about 200 hours of meticulous hand-finishing for each movement in the 25636BA.
Produced in extremely limited numbers, the reference 25636 was crafted in various precious metals—yellow gold (BA), pink gold, white gold, and platinum. Among these, the yellow gold 25636BA was produced for the longest period and in the highest quantity, with only 156 examples known to exist.
The 25636BA is regarded by collectors and Royal Oak enthusiasts as a grail watch, representing the perfect convergence of haute horlogerie, iconic design, and rarity. Its breathtakingly detailed skeletonized movement, combined with the unmistakable Royal Oak silhouette designed by Gérald Genta, makes it one of the most desirable timepieces in Audemars Piguet’s history.
As of today, the Audemars Piguet Royal Oak Perpetual Calendar Openworked 25636BA commands prices between $200,000 and $275,000 on the secondary market, depending on condition.
Key Features:
- Case: 39mm 18k yellow gold case with integrated bracelet
- Movement: Selfwinding calibre 2120/2800
- Perpetual Calendar: Used to display the day, date, month, and moon phase, with a leap year indicator. This watch complication is designed to account of varying lengths of months and leap years, and would not need any manual adjustment until year 2100.
- Openworked Dial: The clear sapphire dial reveals all the components and inner workings of the perpetual calendar movement
