lot 48

Audemars Piguet

Royal Oak Perpetual Calendar Skeleton

Estimate CHF 200 000 / CHF 250 000
Starting bid CHF 200 000

Hammer price CHF 240 000
Total bids 9
Buyer’s premium will not be charged


CaseOctagonal stainless steel case, with a sapphire caseback
BraceletIntegrated stainless steel bracelet
DialSkeletonized dial with white "Chemin de Fer Minuterie" 4 white indicator rings, month and leap year indication at 12 o'clock, date indication 3 o'clock, moonphase indication 6 o'clock, weekday indication 9 o'clock
MovementSkelotonized & engraved rhodium-plated automatic movement, with perpetual calendar
Movement No.592610
Case No.E-94922 / No.433

Condition report

Case:Very good, small signs of wear
Bracelet:Very good, small signs of wear
Dial:Mint Condition
Movement:All functions working properly
Amplitude (Dial on top/Lift angle 52):Approx 280 degrees
Accuracy (Dial on top):Approx + 10 sec/day
Exctract from archives:Yes


An extremely attractive and very rare open-worked stainless-steel perpetual calendar wristwatch of the famous Swiss watch brand Audemars Piguet, founded in 1875. Reference launched most probably in 1996 or 1997, purchase date: 2004. The case in stainless steel, diameter 39mm, thickness 9.3mm, transparent sapphire dial (a so-called ‘skeleton dial’) with leaf-shaped blackened gold hour and minute hands, sapphire caseback. Ultra-thin caliber 2120/2802, self-winding, partially skeletonized and engraved, including self-winding rotor with 21k yellow gold inertia segment, power reserve up to 40 hours. Functions – indication of time in hours and minutes, perpetual calendar with indicators of date, day of the week, month, leap year and moon phase. Royal Oak stainless steel bracelet, Audemars Piguet ‘AP’ stainless steel double folding clasp.

Lot essay

Audemars Piguet launched the present reference in the mid-1990s, most probably in 1996 or 1997, as a replacement for the previous Royal Oak Perpetual Calendar reference 25636 with characteristic open-worked dial. The 25829 differs demonstratively from 25636 models by the presence of a leap year indicator, which is made in the form of an additional small hand on the month counter at 12 o’clock. Phillips auctioneers reported the reference 25829 production span from 1996 to 2013 with 371 pieces made in stainless steel, 102 pieces in yellow gold, 174 in pink gold, 156 in platinum, the limited edition of 25 pieces in steel and platinum, and another limited edition of 2006 with 15 pieces in tantalum and yellow gold, 16 in tantalum and platinum, and 16 in tantalum and pink gold.

The characteristic feature of the reference 25829 design is its transparent dial, through which one can see the details of the complex calendar mechanism with a fine haute horlogerie finish of all parts.

The present example is powered by ultra-thin caliber 2120/2802. The small thickness of the movement made it possible to produce remarkably thin and elegant watches, which is especially significant given the complexity of the function of the perpetual calendar itself. With a thickness of 3.95mm, it remained the thinnest perpetual calendar movement with a central rotor of an automatic winding system until 2018. The Audemars Piguet caliber 2120/2802 is based on a movement-blank supplied by Jaeger-LeCoultre, while the calendar module is based on a kit from the Dubois Dépraz factory. Both are long-term partners and suppliers of Audemars Piguet.

The characteristic feature of the reference 25829 design is its transparent dial, through which one can see the details of the complex calendar mechanism with a fine haute horlogerie finish of all parts. Of particular interest are the leaf-shaped hour and minute hands in blackened gold, which evidently only appear on the dials of the 25829 models.

Reasons to bid

The Royal Oak Perpetual Calendar Open-worked Ref. 25829ST.OO.0944ST.01 would be an excellent purchase for the collector who desires a distinctive wristwatch with a classic perpetual calendar complication in a very rare for Royal Oak collection open-worked execution from a world-renowned traditional watch brand, one of the undisputed leaders in the haute horlogerie watch market. Ref. 25829ST is a classic collector’s item that communicates a certain era in the development of the Royal Oak collection – from approximately 1996 to 2013, when the dial of the Audemars Piguet’s perpetual calendars had the classic indicator of a leap year, but still without the central hand of the indicator of the week of the year, which is a customary feature of modern models made on the basis of clones of caliber 2120/2800. The collector’s value and attractivity of this watch is undoubtedly enhanced by the leaf-shaped hands of a transparent dial, which is unique to the models of the Royal Oak collection.


Commemorating the 50th anniversary of the legendary Royal Oak, this Ineichen Auctioneers sale offers an unprecedented selection of perpetual calendar watches produced by Audemars Piguet since 1982. Royal Oak Perpetual Calendars, which enjoy the active interest of collectors, represent one of the most valuable, admirable and collectible parts of Royal Oak collection heritage. In addition, the Royal Oak Perpetual Calendar remains relevant as a luxurious daily wearer, enriched with practical perpetual calendar function and self-winding movement, one of the best in its category. 

The keen collector should note that also offered for purchase in this sale are other attractive and collectible Royal Oak Perpetual Calendars, including the rarest and most desirable Ref. 25654BA Yellow Gold ‘Tuscany Dial’, superhot Ref. 25820ST ‘Yves Klein’, early Ref. 25654SA C-series ‘Two-tone’, Ref. 25636BA Open-worked ‘The First Generation’, Ref. 25829OR Open-worked ‘All-Rose Gold’, Open-worked ‘Platinum Edition’ Ref. 25829PT, and a magnificent extremely rare Royal Oak Perpetual Calendar Open-worked pocket watch in platinum, among others.