The Audemars Piguet Royal Oak Perpetual Calendar Skeleton reference 25829ST.OO.0944ST.01 is a 39mm luxury sports watch crafted from stainless steel with a case thickness of 9.3mm. It features the iconic octagonal bezel with eight hexagonal screws and an integrated stainless steel bracelet with a folding AP clasp. The timepiece is defined by its transparent sapphire dial and caseback, which reveal the intricately hand-finished and skeletonized movement. This model is powered by the self-winding caliber 2120/2802SQ, an ultra-thin movement that provides approximately 40 hours of power reserve and beats at a frequency of 19,800 vph.
The watch houses a highly sophisticated perpetual calendar complication capable of tracking the day, date, month, and leap year cycles, as well as the phases of the moon. These functions are displayed across four sub-dials: the date at 3 o’clock, moon phase at 6 o’clock, day of the week at 9 o’clock, and the month combined with a leap year indicator at 12 o’clock. Despite the complexity of the mechanism, the watch maintains a relatively slim profile. It is equipped with blued gold leaf-shaped hands and white indicators on the sapphire dial to assist with legibility, while the case is rated for water resistance up to 20 meters.
General reviews of the 25829ST often characterize it as a masterpiece of late 20th-century horology, specifically praising the level of manual craftsmanship involved in the skeletonization and engraving of the movement. Collectors frequently highlight its “Jumbo” 39mm proportions as being more classically balanced compared to later 41mm iterations. While the aesthetic is widely celebrated as mesmerizing and powerful, some critics and owners note that the legibility can be challenging due to the lack of contrast between the skeletonized components and the hands. Nevertheless, it remains a highly coveted reference for its historical significance as one of the last great hand-decorated Royal Oak perpetual calendars.