Launched in 2011 as part of the Patek Philippe Advanced Research series, the ref. 5550P was created to showcase the manufacture’s Oscillomax® escapement in a classic perpetual calendar wristwatch. While outwardly restrained, the ref. 5550P is one of the most technically significant Patek Philippe references of the modern era. Also it is one of the only modern Patek Philippe watches to mix metals – the platinum case and rose gold batons on the dial make and unforgettable match.
At its heart is the automatic caliber 240 Q Si, a special version of Patek Philippe’s legendary ultra-thin perpetual calendar movement. The “Si” designation refers to the use of Silinvar®, Patek Philippe’s silicon-based material, incorporated in the Spiromax® balance spring, Pulsomax® escapement, and GyromaxSi® balance. Together, these innovations improved rate stability, reliability, and power reserve while preserving the architecture and refinement of one of Patek Philippe’s most beloved perpetual calendar calibers. A magnified cyclops lens within the sapphire case back allows the wearer to properly inspect the impressive technology within.
The exterior remains beautifully traditional. The 37 mm case is crafted in platinum with curved lugs, a rounded bezel, and the discreet diamond set at 12 o’clock, an unusual placement required because the moon-phase correction pusher is positioned between the lugs at 6 o’clock. The vertically satin-finished silvered dial is clean, balanced, and unmistakably Patek Philippe, with day, date, month, leap year, 24-hour indication, and moon phases arranged with exceptional clarity.
This example, made and sold in 2012, is full set, accompanied by its Certificate of Origin, winding presentation box, additional solid platinum case back, setting pin, and literature. For collectors seeking an important modern Patek Philippe that combines rarity, technical innovation, and classical perpetual calendar design, the ref. 5550P is a standout.
