In 1984, twelve years after the unprecedented launch of the Royal Oak, Audemars Piguet further railed against the changes brought by the quartz crisis and released the Royal Oak Perpetual Calendar. It was no easy feat to fit an automatic caliber with perpetual calendar and moon phases, within a case measuring only 8.8mm in thickness.

The brand would soon introduce a new design aesthetic, offering the Royal Oak perpetual with skeletonized dials and movements, which were virtually non-existent on wristwatches in the 1980s. These fully skeletonized watches allowed for a breathtaking view of the movement from both the front and back. They exemplified the very best of Swiss watchmaking, where non-essential metal from all the movements’ plates and bridges were removed, and all remaining “skeletal” parts were hand-engraved and finished.

According to Audemars Piguet, 156 pieces in yellow gold were produced between 1986 and 1997, with only 10 examples leaving the factory in 1994. In total for the reference, 313 pieces were produced across all materials. It was the first Royal Oak reference to feature a sapphire caseback, displaying for the first time the spectacular hand-engraved movement. The contrasting colors of the movement parts – some steel, some gold-plated, some solid gold – allow for a beautiful contrast below the sapphire dial, with the champagne subdial rings floating above. Impressively, the present reference 25636 retains its original guarantee booklet, indicating the watch was sold on February 24th, 1994.