Patek Philippe Perpetual Calendar ref.5327G-001 from 2021

This watch is not only a work of art but also an engineering marvel, utilizing the same movement that has been present in Patek perpetuals for over 35 years: the caliber 240Q, featuring a micro-rotor, a favorite among many purists.

In our modern technological era, the calendar serves as a connection to the natural world, aligning the rhythms of the Earth and the sky with those of human life. Naturally, a mechanical watch that tracks the progress of the calendar must incorporate these cosmic rhythms into gear patterns and proportions. These include the speed at which the Earth rotates on its axis, forming the day; the Moon's orbit around the Earth, giving us the month; and finally, the Earth's orbit around the Sun, marking a year.

The highest order of such watches is the perpetual calendar, as it requires a high degree of automation, specifically, an annual reiteration. It must adhere to the dictates of the Gregorian calendar, where each leap year has 366 days instead of the usual 365, adding an extra day to February. This means that the mechanism must accurately account for all calendar irregularities, transitioning at the end of each month, advancing to the first day of the next month, sometimes after 30 days and other times after 31 days. It adjusts on the 28th of February each year and finally, extends February by one day every four years. The complexity of encoding these rules makes the gear train of a perpetual calendar one of the most intricate, perhaps surpassed only by a minute repeater, which ironically tells only the time.

However, a perpetual calendar, despite its name's optimism, is not eternal. By design, a perpetual calendar overlooks the one rule that distinguishes the Gregorian from the Julian calendar—century years are leap years only if divisible by 400. The mechanism would consider the years 2100, 2200, and 2300 as leap years when they are, in fact, common years. In other words, a perpetual calendar will correctly recognize the duration of each month, whether it contains 28, 29, 30, or 31 days, until the year 2100, before requiring manual intervention.

Brand: Patek Philippe
Model: Perpetual Calendar
Reference:5327G-001
Year of Manufacture: 2021
Material: White Gold
Dimensions: 39 mm
Crystal Material: Sapphire
Movement Type: Self-winding mechanical movement.
Caliber: 240 Q
Strap Measurement: 19.5mm
Strap: Alligator skin with square scales, hand-stitched, blue.
Buckle: White Gold
Box/Papers: Watch and box
Mechanical Operation Warranty: 6 Months