This Perpetual Calendar Royal Oak 25820ST* features a striking combination of the iconic Royal Oak case, an unusual indigo blue dial and a perpetual calendar movement central to the manufacture’s history. An example that showcases one of the more elegant variations of the Royal Oak, it is an excellent find for collectors searching for a more subtly special piece.

Since its introduction, Audemars Piguet has used the Royal Oak Perpetual Calendar as a canvas to experiment with different metal combinations and dial designs. From the tantalum two-tone examples to openworked dials, the collection offers a rich variety of configurations, where the manufacture has pushed the boundaries of conventional design.

This example, with its deep blue dial, speaks to that approach. This seldom seen, navy blue tone is indicated as “.05” at the end of the reference number on Certificate of Warranty and Authenticity. Evidence suggests the dial was manufactured by Stern Creations, the famed manufacturer of dials, which also made dials for the original Royal Oak ref. 5402.

The layout of the dial includes all the traditional indications of a perpetual calendar: day, date, astronomical moon (with graduation for moon age) and month. It features original luminous-filled baton hands, a feature typically found in Royal Oak watches, where the index markers are also luminous. The sub-dials are slightly recessed, giving the dial greater depth and texture. It features the "Audemars Piguet" signature in the more modern lettering, adopted by the brand towards the end of the millennium.

It retains the more understated “Grande Tapisserie” pattern, forming the square and lozenge motif, as seen in earlier executions of the Royal Oak. Some newer versions of the Royal Oak have since adopted AP’s bolder “Tapisserie Evolutive” dial pattern, less faithful to the original design. The deep indigo colour is complemented by crisp white indications used throughout the dial.

The stainless case and bracelet are excellently finished, with angular, beveled and polished edges - striking the perfect balance between utilitarian function and elegant design. The polished screws, bezel and case edges fantastically-contrast with the brushed surface of the case and bracelet. At 39mm in diameter, and only 9.3mm thick, this Royal Oak Quantième Perpétuel case sits comfortably on the wrist. On the reverse, the outer caseback correctly displays the unique serial number (F-68XXX), along with its case number (6XX).

This Royal Oak Quantième Perpétuel is powered by the AP caliber 2120/2802, derived from Jaeger-LeCoultre’s legendary ultra-thin JLC 920 calibre movement. The caliber 2120 was an initial project of Jaeger LeCoultre in 1967, funded and contributed by Audemars Piguet, and famous for its adoption by Audemars Piguet, Patek Philippe and Vacheron Constantin.

The ultra-thin automatic 2120/2800 calibre features 38 working jewels, Gyromax balance and four ruby wheels to support the full-diameter rotor, which runs on a beryllium rail for stability. The AP calibre 2120 remains the thinnest full-rotor self-winding movement in the world, considered by many as one of the most technically refined wrist-watch movements ever made.

If sold within the United Kingdom, this Audemars Piguet Perpetual Calendar will be subject to 20% VAT

Closer look

Condition

This Audemars Piguet Perpetual Calendar is in very good overall condition. The case and lugs show light superficial marks on the polished portions of the case, otherwise retaining strong proportions and the correct finishing throughout. The dial is free from any imperfections and has aged to an attractive indigo blue, and the movement is free from any signs of imperfections. The engravings on the caseback are crisp and well defined.

The watch comes directly from the original owner and has been very well kept, receiving a service from the manufacturer twice, once in 2019 and most recently this year. The set is complete with its outer box, inner wooden winding box, certificate of authenticity, and perpetual pusher. The owner went to the extent of purchasing an additional leather strap, including an additional AP deploying buckle and end links suitable for the reference.

Warranty

The watch was recently serviced by Audemars Piguet in March 2024 and thus comes with time remaining on the brand's servicing warranty. The watch also comes with a lifetime guarantee of authenticity from  A Collected Man.