Watch Wiki

The Best Watches and Watch Brands

User Tools

Site Tools


Patek Philippe Perpetual Calendar 5550

Patek Philippe Perpetual Calendar 5550 (click to enlarge!)
Patek Philippe Perpetual Calendar 5550
© Patek Philippe

Patek Philippe's 2011 Perpetual Calendar Ref. 5550 was one of the first wristwatches with a silicon balance wheel. It is the fourth member of their Advanced Research project.


In the 2000s, Patek Philippe set up an Advanced Research project to address the long-standing issues of isochronism and durability in watches. The main technology applied to this task was a proprietary alloy of silicon known as “Silinvar”. The company proceeded steadily, producing first a Silinvar escape wheel, then a hairspring, an anchor, and a balance.

Ref. 5550 was the fourth Advanced Research watch, introduced in 2011, and the first with a perpetual calendar. Cal. 240 Q Si included the Silinvar “Pulsomax” escapement of its predecessor, this time in the company's fine micro-rotor automatic movement. It also added a novel Silinvar version of the company's traditional Gyromax balance wheel with a 24 karat gold rim and four gold poising screws called GyromaxSi. This made it one of the first watches ever produced with a silicon balance and escapement. The display caseback included a large “cyclops” magnifier to allow the owner to inspect these high-technology components.

Although it used these high-tech components, Ref. 5550 was nevertheless a Patek Philippe. It included their traditional perpetual calendar mechanism with day/24 hour indicator and month/leap year indicator subdials inset at 9 00 and 3 00, and a date and moon phase subdial at 6 00. The silver dial features simple applied gold markers at all hours but 6, and a “railroad” seconds track. The hour and minute hands were leaf shaped and featured lume. It had a traditional Patek Philippe platinum case, with long integrated lugs.


  • 5550 platinum, 300 produced




  • Silver


Limited edition:

patek_philippe_perpetual_calendar_5550.txt · Last modified: 02.12.2022 20:43 by

Donate Powered by PHP Valid HTML5 Valid CSS Driven by DokuWiki

© Watch Wiki. All texts are protected by copyright. The respective copyright holders are the signatories of the contributions. For details see Impressum. Regarding objections and complaints (copyright and other rights) also see there. Impressum | Privacy Policy | Copyright | About Watch Wiki