Audemars Piguet Royal Oak Chronograph ’50th Anniversary’ 41mm 18kt Rose Gold with Blue Nuit Nuage 50 "Grande Tapisserie" Dial, Sapphire Crystal Skeleton Exhibition Case Back, Fitted on a Blue Hand-Stitched Alligator Strap with 18kt Rose Gold Deployant Buckle. 

The 41mm diameter solid 3-body case, angled lugs, bracelet, and octagonal bezel with 8 white gold hexagonal face screws, are brushed/polished. It has a Blue Nuit Nuage 50 "Grande Tapisserie" Dial with applied rounded and luminous baton hour markers around a white perimeter minute/second scale, rounded luminous baton hour and minute hands, and there is a center sweep second hand with an open oval counterbalance. The date aperture is between 4 and 5 o’clock, and it includes three recessed blue subsidiary dials with white Arabic numerals, markers, and indicator hands, including a small constant running seconds register at 6 o’clock, a 30-minute chronograph counter at 9 o’clock, and there is a 12-hour chronograph totalizer at the 3 o’clock position. 

This Audemars Piguet Royal Oak Chronograph "50th Anniversary" 26240OR.OO.D315CR.01 has an automatic self-winding AP caliber 4401 fly-back column wheel chronograph movement. It’s rhodium plated with perlage and Cotes de Geneve embellishment and it’s constructed with 37 jewels, an anti-shock system, a 21k white gold Anniversary rotor, a monometallic balance, and the mechanism oscillates at a frequency of 21,600 vph (3Hz).

The dial’s Bleu Nuit, Nuage 50 hue was originally developed by Geneva-based dial maker Stern Frères. The blue colour was obtained by immersing each dial in a galvanic bath. While the formulation of the mixture is important, the duration and temperature are both crucial. If the artisan removes the dial too early, it comes out purple, if removed too late it turns black. A thin layer of varnish mixed with a few drops of black colour (n° 50) was then applied onto the dial to protect it. The term “nuage” refers to the cloud effect the drop of black creates when it enters the protective liquid varnish. Today, the Bleu Nuit, Nuage 50 hue is achieved internally through PVD (Physical Vapor Deposition) to ensure a more homogeneous colour across the collection.

This rare new Royal Oak “50th Anniversary” timepieces is fitted with the dedicated oscillating weight in 22-carat gold that features the “50-years” logo and the engraved Audemars Piguet signature. For the occasion, the oscillating weight has been matched to the colour of each case and finished with an alternation of satin-finishing and polished chamfers.

Faithful to the aesthetic of the original model from 1972, numerous references across the Royal Oak collection now welcome the iconic Bleu Nuit, Nuage 50 dial colour (“night blue, cloud 50”), combined with a Petite or Grande Tapisserie pattern.

REF# 26240OR.OO.D315CR.01