The Audemars Piguet Royal Oak Perpetual Calendar Ultra Thin (ref. 26586BA.OO.1240BA.99) showcases the maison’s technical virtuosity in a strikingly slender profile. Released in 2023 as a limited edition of just 88 pieces, this yellow gold execution of the pioneering Ultra Thin QP combines mechanical complexity with sharp, architectural aesthetics in unmistakable Royal Oak form.

Crafted in solid 18ct yellow gold, the 41mm case stands only 6.2mm tall – a remarkable feat for any perpetual calendar. Beneath the sapphire crystal, a matching yellow gold-toned dial carries subdials for day, date, month, and moonphase, all symmetrically arranged for optimal legibility and balance. The ultra-thin calibre 5133, measuring just 2.89mm thick, enables the watch’s svelte case while offering a full Gregorian perpetual calendar complication. The integrated gold bracelet continues the geometric fluidity of the watch’s tonneau-linked design.

At the time of its release, it was the thinnest self-winding perpetual calendar ever made – a benchmark piece in both AP’s history and modern watchmaking. With only 88 made, it remains one of the rarest iterations of the Royal Oak for collectors seeking apex engineering in a warm gold palette.