Earlier this year, in February 2025, Audemars Piguet celebrated its 150th anniversary with the release of the Royal Oak Perpetual Calendar Openworked “150th Anniversary” (ref. 26585XT), a limited edition of just 150 pieces. This timepiece stands as both a tribute to the manufacture’s heritage and its pursuit of innovation, craftsmanship, and design mastery.
The watch marks the final appearance of the Caliber 5135, the skeletonized version of the Caliber 5134 that has powered Audemars Piguet’s openworked perpetual calendars since 2015. After nearly a decade of service, the retirement of this movement underscores the significance of the anniversary edition, making it both a technical and historical milestone.
Design inspiration for the watch comes from Audemars Piguet’s openworked perpetual calendar pocket watch ref. 25729PT from the 1980s. That pocket watch, crafted in platinum with a sapphire dial, diamond-set indices, and blue accents highlighting its skeletonized bridges, serves as the aesthetic blueprint for the modern anniversary model. The Royal Oak translates these cues into a wristwatch: its sapphire dial reveals the intricate architecture of the Caliber 5135, while a brass blue inner bezel and deep blue sub-dials echo the vintage original. The perpetual calendar retains its familiar layout, with the month and leap-year indicators at 12 o’clock, date at 3 o’clock, weekday at 9 o’clock, and moon phase at 6 o’clock. Silver-grey round indices recall the diamond markers of the pocket watch, while blue “bathtub” hands in 18k white gold with luminescent coating ensure legibility.
The case design further distinguishes this limited edition. Measuring 41mm in diameter and just 9.9mm thick, the titanium midcase is framed by a polished bulk metallic glass (BMG) bezel and caseback. The integrated titanium bracelet features polished BMG studs for a subtle but striking contrast, while sapphire crystals on both sides provide an unobstructed view of the movement. With water resistance of 20 meters, the piece balances refinement with practicality.
Limited to 150 pieces and priced at 175,000 CHF, the Royal Oak Perpetual Calendar Openworked “150th Anniversary” is both a collector’s piece and a farewell to one of Audemars Piguet’s most distinctive movements.
