Patek Philippe Annual Calendar 5350

Patek Philippe's 2006 Annual Calendar Ref. 5350 was one of the first wristwatches with a silicon balance spring ever produced. It is the second member of their Advanced Research project.

Overview

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. 5350 was the second Advanced Research watch, introduced in 2006. Cal. 324 S IRM QA LU included the Silinvar escape wheel of its predecessor and added a flat Silinvar hairspring to the mix. This made it one of the first watches ever produced with such a spring. The display caseback includes a large "cyclops" magnifier to allow the owner to inspect these two high-technology components.

Although it used these high-tech components, Ref. 5350 was nevertheless a Patek Philippe. It included their revolutionary annual calendar mechanism with day and month subdials inset at 10:00 and 2:00, a date window below the moon phase indicator at 6:00, and a simple "+/-" power reserve indicator at 12:00. The dial features Arabic numerals at 3, 9, and 12, applied markers at all other hours but 6, and a "railroad" seconds track. The hour and minute hands are leaf shaped and feature lume. It has a traditional Patek Philippe pink gold case, with long integrated lugs.

Reference: 5350 pink gold, 300 produced Movement: Automatic manufacture movement: Caliber 324 S IRM QA LU, 28,800 A/h Annual calendar module Silinvar escape wheel with Silinvar Spiromax balance spring Geneva Seal Case: Pink gold D 39 mm, H 11.7 mm Sapphire crystal caseback with magnifying bubble Dial: Silver Functions: Hours, minutes, central seconds Annual calendar with day, date, month Moon phase indicator Limited edition: 300 pieces Predecessor: Patek Philippe Annual Calendar 5250 Successor: Patek Philippe Annual Calendar 5450