Audemars Piguet Royal Oak Perpetual Calendar Openworked “150th Anniversary”
Audemars Piguet celebrates its 150th anniversary with a striking new addition to the Royal Oak Perpetual Calendar Openworked collection. This limited edition of 150 pieces marks the final appearance of the in-house Calibre 5135, a movement that has powered the brand’s openworked perpetual calendar models since 2019. Blending traditional craftsmanship with cutting-edge materials, the watch combines a titanium case with Bulk Metallic Glass (BMG) elements, offering a contemporary take on a historically significant complication. With a dial inspired by a vintage pocket watch from the Musée Atelier Audemars Piguet, this release embodies both technical innovation and timeless aesthetic refinement.
This 150th Anniversary edition is housed in a 41mm titanium case with a 9.9mm thickness, maintaining the signature octagonal bezel and integrated bracelet of the Royal Oak collection. Unlike previous openworked perpetual calendar models, this anniversary edition incorporates Bulk Metallic Glass (BMG) elements, which appear on the bezel, caseback frame, and bracelet studs, creating a subtle yet striking contrast against the lightweight titanium case. The combination of these materials enhances durability, scratch resistance, and corrosion resistance, while also giving the watch a distinctive shine compared to traditional metals.
On the rear is a screw-down caseback that features a titanium frame with BMG inserts, offering a clear view of the openworked Calibre 5135 through a sapphire crystal. In celebration of the brand’s 150th anniversary, the caseback is engraved with “150” and “1 of 150 pieces,” reinforcing the exclusivity of this final edition.
The screw-locked crown, positioned at 3 o’clock, ensures easy handling and is finely engraved with the AP logo. Sitting flush with the case, the anti-reflective sapphire crystal provides a clear, distortion-free view of the intricate openworked dial. Water resistance can reach up to 20 meters (66 feet).
Time is exhibited on a striking blend of heritage and innovation, inspired by a historical openworked perpetual calendar pocket watch (ref. 25729) from the Musée Atelier Audemars Piguet. The intricate skeletonized movement is displayed in full view, allowing a glimpse into the mechanics of the Calibre 5135, while a deep blue inner bezel and subdial rings provide contrast against the silver-grey hour markers. This vintage-inspired color palette gives the watch a sophisticated, refined aesthetic that pays tribute to the brand’s long-standing expertise in perpetual calendars.
The hour markers are crafted in a rounded, silver-grey finish, subtly mirroring the brilliant-cut diamonds found on the historical pocket watch. To maintain legibility, the numerals and letters on the perpetual calendar indicators are executed in a clean, white typeface, specifically refined for this edition.
The bathtub-shaped hands are crafted from 18k white gold and filled with luminescent material, ensuring optimal readability in various lighting conditions. This attention to detail not only enhances the luxurious appeal of the watch but also reinforces its technical precision.
At 6 o’clock, the moon-phase display is a standout feature, showcasing a realistic lunar depiction based on NASA imagery. This photographic representation of the Moon, transferred onto a sapphire disc using metallization, accurately depicts the eight phases of the 29.5-day lunar cycle. Unlike conventional moon-phase designs, this display is visible from both the northern and southern hemispheres, ensuring a balanced presentation within the dial’s complex layout.
Audemars Piguet Royal Oak Perpetual Calendar Openworked “150th Anniversary”
This “Audemars Piguet Royal Oak Perpetual Calendar Openworked “150th Anniversary” (Ref#: 26585XT.OO.1220XT.01) is powered by the self-winding in-house mechanical movement, caliber AP 5135 with 38 jewels, 374 components and 19,800 vph. 
AP developed two patented innovations to enhance the accuracy of the calendar mechanism: the end-of-the-month cam, which is integrated into the date wheel, and the month cam, which is directly combined with the month wheel. These refinements allow for seamless transitions between months, ensuring precise tracking of leap years and perpetual calendar functions without manual intervention. Power reserve can last up to 40 hours, when fully wound.
Mounted on the watch is a titanium bracelet with BMG studs, maintaining the lightweight yet durable construction of the case. The bracelet’s surfaces alternate between satin-brushed and polished finishes, reflecting Audemars Piguet’s signature attention to detail. A titanium AP folding clasp ensures a secure and comfortable fit on the wrist. This reference is limited to 150 pieces, making it a highly exclusive collector’s piece. 
For more up to date information visit the official Audemars Piguet website here.
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