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A perpetual calendar, alongside chronographs and repeater, is one of the more exclusive complications that make a watch a true luxury watch and an example of Haute Horlogerie. For many watch collectors, investing in a watch with one, if not several unique complications is often the highlight of their own watch collection. We will take a closer look at what exactly a perpetual calendar is and how this complication ended up on our wrists.

  1. What is a perpetual calendar?
  2. How a perpetual calendar works
  3. Tips on setting a perpetual calendar
  4. The first watches with a perpetual calendar
  5. Should I buy a watch with a perpetual calendar?

What is a perpetual calendar on a watch?

Put simply, a perpetual calendar on a watch allows the indication of the day of the week for any given year. Carl Friedrich Gauss provided the corresponding algorithm in 1800, but the term "perpetual" must be regarded relatively for luxury watches. There are watches with a perpetual calendar that display the date correctly until the year 2100 without having to adjust the date. In 2100, however, some watches with a perpetual calendar will switch from February 28th to February 29th, although the leap year will be cancelled this year. The reason for this is a major change to our calendar from the 16th century.

A calendar reform and its significance for luxury watches

In 1582, the Gregorian calendar, the common Western and Christian calendar, replaced the Julian calendar. This was done by a reform decreed by Pope Gregory XIII, which was intended to counteract the continuing shift in the astronomical beginning of spring and thus the date for the Christian celebration of Easter. The shift came about because the Julian calendar was 11 minutes longer than a solar year. This led to a shift of the beginning of spring by one day every 130 years. The Gregorian calendar was not a new invention, but used the counting scheme of the Julian calendar and made it flexible for the future. The average calendar year now had a length of 365.2425 days instead of the previous 365.25 days. Additionally, there was a new provision for leap years. This particularly interesting for buyers and owners of luxury watches with a perpetual calendar. The rule specifies that secular years (e.g., 1700, 1800, 1900, 2100), which can be divided by 400 without resulting in an integer, are not leap years. For this reason, the calendar must be manually changed to February 28th in 2100. However, there are some important points to consider.

Maurice Lacroix Masterpiece Calendier Retrograde 76840-1702 watch with a perpetual calendarMAURICE LACROIX MASTERPIECE CALENDRIER RETROGRADE 76840-1702

How does a perpetual calendar work?

Naturally, the watchmakers capable of producing a complication for a perpetual calendar have also developed different mechanisms. Therefore, here is a simplified explanation of how a perpetual calendar works.

First, it is assumed that there are 28 days in each month. On the 25th of the month, the movement then determines how many extra days need to be added. For leap years, this means February 29th or the days until 30th or 31st of the remaining months. A program wheel in the month display controls the four-year rhythm for leap years.

What should be considered concerning the perpetual calendar on a watch?

The intricate mechanics behind the complication of a perpetual calendar are extremely delicate. That is why there are a few things that need to be taken into account to ensure that you can enjoy the functionality of your timepiece with a perpetual calendar for a long time:

  • Set the date, when the hands are between 6:00 AM and 6:00 PM
  • Never change the date between 11:00 PM and 1:00 AM
  • Never attempt to turn the date back
  • Do not set the time by adjusting it in reverse

With the right instructions and some helpful tips, you can easily set your watch and you don't have to worry about damaging anything.

How long have watches featured perpetual calendars?

The invention of the first pocket watch with a perpetual calendar is attributed to the English watchmaker Thomas Mudge in 1764. A century and a half later, Patek Philippe designed the first wristwatch with a perpetual calendar. The company from Geneva is still renowned today for its sophisticated complications. The Grand Complications series includes unique pieces featuring a variety of exclusive complications. Since the advances of Patek Philippe in the 1920s, many watch manufacturers have taken up the challenge of fitting their watches with a perpetual calendar function. In the 1940s, Patek Philippe took another step forward by producing a chronograph with a perpetual calendar. The first automatic watch with this complication followed almost 20 years later.

IWC Da Vinci Rattrapante IW375401 watch with a perpetual calendarIWC DA VINCI RATTRAPANTE IW375401

IWC Schaffhausen also deserves a mention among the producers of fine timepieces. In the 1980s, IWC designer Kurt Klaus came up with an innovation of the perpetual calendar after the quartz crisis. The aim of this new movement was to make it as convenient to use as possible by providing a quick date adjustment and a simplified complication design in order to allow for series production. This led to various models, such as the IWC GST Perpetual Calendar (Ref. IW375609) or the IWC Da Vinci (Ref. 3735).

Is buying a watch with a perpetual calendar a good investment?

Many watch collectors buy a luxury watch not only based on its functionality. What matters is the enthusiasm that a watch model evokes and the high degree of craftsmanship behind such a watch. Be it the perfect design or the precise craftsmanship with which the watch runs, if you are looking for a pre-owned watch with a perpetual calendar, you will quickly find one in the Watchmaster online shop. An investment in this type of watch can quickly reach the upper four-figure range, but the purchase of a used luxury watch with a perpetual calendar is by no means to be compared with buying an everyday watch. With such a timepiece, you are placing an example of the highest craftsmanship on your wrist. Especially with luxury watches from Jaeger LeCoultre, Harry Winston and Vacheron Constantin, a purchase is worthwhile after a few years, as these coveted masterpieces often increase in value.

Vacheron Constantin Perpetual Calendar 43031 with a perpetual calendarVACHERON CONSTANTIN PERPETUAL CALENDER 43031

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