The Royal Oak RD#2 Perpetual Calendar Ultra Thin by Audemars Piguet is the thinnest self-winding perpetual calendar in the world at just 6.3 mm thickness. It is 41 mm in diameter, with case and bracelet in platinum. The surprising thing about the RD#2 is that, like the Royal Oak Concept RD#1, it is not yet a production watch but a research and development timepiece. It’s surprising because the case, like the entire watch, looks absolutely classical.
A dial of high legibility
The dial is a masterpiece of legibility, with a lovely astronomical moon phase display, subdials for day, month and date, and the leap year cycle indicator on a small subdial at 4 o’clock. The latter is balanced by a day-night indicator at 8 o’clock. It’s a nice design touch, and it compares well with (to mention another recent perpetual calendar watch) the Chopard L.U.C Perpetual Chrono in platinum, in which the same two miniature subdials are arranged a bit like Mickey Mouse ears. The Chopard watch is hand-wound and 15.06 mm thick, which gives an idea of the incredible achievement represented by the Audemars Piguet watch.
Platinum case and strap
Even though it’s ultra-thin, this watch is still quite heavy. The case, bezel and integrated bracelet are all in platinum. Somehow the weight and the moderate thickness – not wafer thin like the Piaget record breakers – make it feel reassuring on the wrist. Water resistance is 2 bar, 20 metres.
Calibre 5133 is based on calibre 2120, which is the thinnest movement with a full-size oscillating weight in production, and it has been so since 1967. The 2120 has a balance that runs at 2.75 Hertz, 19,800 vibrations per hour, and so the 5133 inherits this. But the new RD#2 perpetual calendar movement is not just a modular version of the 2120. To achieve a thickness of 2.89 mm, the Audemars Piguet designers rethought the perpetual calendar mechanism completely, combining components that are normally separate, and using the reverse of the dial as the mainplate. The movement has a power reserve of 40 hours.
Price and reference
The Royal Oak RD#2 by Audemars Piguet is reference RO 26586PT.OO.1240PT.01. For the moment it is not a production watch, but, just as for the RD#1, it will probably be marketed in the near future. See the Audemars Piguet website for further information.