WHAT IS SPECIAL
The Audemars Piguet Royal Oak Perpetual Calendar ref. 25820 is the last 39mm perpetual calendar made in the original Royal Oak proportions. Produced from 1996 until 2013, it represents the final chapter of the classic ultra-thin 39mm Royal Oak before the brand shifted to larger, thicker 41mm cases and bracelets. It marks the transition from the original design philosophy to a more modern direction.
At 39mm, the 25820 stays true to the Royal Oak’s original ultra-thin concept. As the second-generation Royal Oak perpetual calendar, it added a leap year indicator — a practical upgrade over the first generation. Interestingly, Audemars Piguet was actually the first brand to introduce a leap year display on a perpetual calendar wristwatch, decades before Patek Philippe adopted it.
Over its 17-year run, the 25820 was made in far smaller quantities than today’s Royal Oaks. Platinum versions were especially rare, with only around four to five pieces produced per year — and salmon dial examples are even scarcer. In platinum on bracelet, the weight on the wrist is substantial and deeply satisfying. Beautiful to look at, and even better to wear.