25829BA Audemars Piguet Royal Oak QP Skeleton

The 25829BA is the Royal Oak QP Skeleton in yellow gold, the second generation of skeletonized RO QP and the first with a leap year indication. Introduced in 1996 and produced in small batches through roughly 2009, it captures a very specific moment: Switzerland emerging from the quartz crisis with something to prove. The skeletonized QPs were how the great houses showed off to themselves, and AP's was arguably the most daring—a razor-thin grand complication in Genta's steel-sport case architecture, stripped to its bones. Per AP's archives, just 102 examples of this reference were made in yellow gold, alongside 371 in steel, 174 in pink gold, 156 in platinum, 25 in steel-platinum, and 47 in tantalum combinations—a total run under 900 across all metals over nearly two decades.

Its bloodline runs through AP's most important calibre. The 2120/2800 was developed in secret during the darkest years of the crisis by three senior watchmakers—Michel Rochat, Daniel Golay, and Wilfred Berney—who worked after-hours, unpaid, fearing the budget would never be approved. Built on the JLC 920 ébauche, it debuted in the 5548 of 1978 as the world's thinnest self-winding perpetual calendar. The first skeletonized Royal Oak QP, the 25636, followed in 1986.

The 25829 arrived a decade later carrying calibre 2120/2802, the evolution that added the leap year display. The dial is sapphire, the bridges worked down, engraved, beveled, and finished by hand. Cases grew marginally thicker for proper water resistance, hands went to a romantic feuille shape, and early yellow gold examples wore beige counters before AP switched to white around 2005.

Plenty of complicated sport watches feel contrived today. This one never has. It was a real watchmaking risk from a manufacture that had already bet the house once on the 5548 and won. At 39mm and impossibly thin, the 25829BA is warm, technical, and quietly rare in a way modern limited editions can only imitate. It's one of the last great Royal Oak QPs, from the era when AP made watches for watchmakers first. The full-gold skeleton QP is the era's thesis statement, and this is it.

This example comes with the complete works, including all the set. It hails from 2007 and is currently with a well-regarded retailer in Italy.