Audemars Piguet Royal Oak Perpetual Calendar Gem-Set

About this reference

The Audemars Piguet Royal Oak Perpetual Calendar reference 25659BA was produced during the late 1980s and early 1990s. This 39mm 18k yellow gold model is distinguished by its factory gem-setting, typically featuring a diamond-set bezel and hour markers. It utilizes the ultra-thin automatic caliber 2120/2800, a movement derived from the Jaeger-LeCoultre 920 base. Collectors value this reference for its "Jumbo" proportions and its role in the evolution of the perpetual calendar complication within the Royal Oak line. Production numbers for gem-set variants were significantly lower than the standard 25654 or 25820 references, contributing to its scarcity. On the secondary market, these pieces generally command prices in the mid-to-high six-figure range depending on provenance and condition. A notable example featuring a "Tuscan" texture dial and factory diamonds sold at auction for over $400,000, reflecting the premium placed on rare dial configurations.