Audemars Piguet Royal Oak Perpetual Calendar Openworked

About this reference

The Audemars Piguet Royal Oak Perpetual Calendar Openworked reference 25636PT was produced between approximately 1993 and 1996. Collectors prioritize this reference for its combination of a 39mm "Jumbo" ultra-thin case profile and the caliber 2120/2800, a self-winding movement featuring a hand-finished skeletonized structure. Unlike standard perpetual calendars, the 25636 lacks a leap year indicator, a characteristic of early Royal Oak complications. The platinum construction represents the rarest metal variant of this reference, with production estimated at fewer than 35 units. This scarcity, paired with the transition from the "Quantième Perpétuel" era to modern aesthetics, places secondary market values in the mid-to-high six-figure range, often exceeding $400,000 depending on provenance. A notable 2023 auction result at Phillips saw a well-preserved example achieve over $600,000, underscoring the demand for low-production platinum skeletonized Royal Oaks among high-level collectors.