The perpetual calendar is one of the masterpieces of haute horlogerie, as this long-term genius knows the correct length of months even in leap years. Only in 2100, when, according to the Gregorian calendar, the leap year is omitted, does the complex mechanism require manual correction. However, the challenge lies not only in the mechanical “programming” but also in presenting the numerous calendar-related information in a clear and concise manner within the limited surface of the dial.

One of the most beautiful examples of the genre was achieved by A. Lange & S?hne with the Lange 1 Perpetual Calendar, first presented in 2021. In order to preserve the signature design of the Lange 1 watch family with its off-center and non-overlapping displays, Lange’s watchmakers opted for a completely new approach and developed a peripheral month ring that advances instantaneously at the end of each month. Premiered in 2012 with the launch of the Lange 1 Tourbillon Perpetual Calendar, this innovative mechanism replaces the traditional design where the month display is controlled by a 48-step cam.

“The commitment to tailor the complex mechanical requirements to the characteristic design of the Lange 1 presented our developers with constructive challenges, as the large peripheral ring has to be advanced instantaneously by 30 degrees from one month to the next. Throughout the month, energy is collected via a cam in order to provide the required power exactly on time, at midnight on the last day of the month,” explains Anthony de Haas, Director of Product Development. “Thanks to this design feature in the Lange 1 Perpetual Calendar, this watch family’s distinctive face could be maintained.”

Adding a day/night indication to the moon-phase display is also typical of the manufacture’s continued quest for precision and new ways to bring it to life. Designed across two levels, it consists of a solid-gold celestial disc with graduated blue hues that rotates around its own axis once during 24 hours. Against this backdrop, the white-gold moon performs its synodic orbit in 29 days, 12 hours, 44 minutes and 3 seconds – with such precision that the display only needs to be corrected by one day after 122.6 years. First implemented in the Lange 1 Moon Phase in 2016, the indication depicts the earth’s satellite moving across a bright-blue sky during the day and a dark-blue starry sky at night, thus indicating the diurnal and nocturnal hours respectively.

Platinum case and black dial

The initial white-gold model version with a solid pink-gold dial, limited to 150 pieces, and the pink-gold version featuring a grey solid-silver dial are now joined by a platinum execution with a black dial (above). The dark background creates a beautiful contrast to the moon phase and exudes a very elegant charisma. As with the previous versions, the month ring provides the framework for all the displays – large date, weekday, leap year and moon phase with integrated small seconds. All calendar indications switch instantaneously and therefore produce unambiguous readings at any given time. They can be advanced collectively or separately with correctors.

The artisanal excellence maintained by the Saxon manufacture is immediately evident when you glance through the sapphire crystal case back. As is de rigueur for Lange, the caliber L021.3, which comprises of 621 parts, is meticulously hand-finished. The technical highlights of this in-house movement include a unidirectional winding rotor made of 21-carat gold, with a centrifugal mass crafted from 950 platinum.

The self-winding movement oscillates at a frequency of 21,600 semi-oscillations per hour and boasts a power reserve of 50 hours. Its plates and bridges are crafted from untreated German silver and adorned with Glash?tte ribbing. Five gold chatons secured by blued-steel screws and the balance cock, hand-engraved and featuring the whiplash spring mounted above for beat adjustment, exemplify the manufacture’s commitment to a high standard in every detail.

Pricing for the A. Lange & S?hne Lange 1 Perpetual Calendar is available per request.

To learn more, visit A. Lange & S?hne, here.

 The perpetual calendar is one of the masterpieces of haute horlogerie, as this long-term genius knows the correct length of months even in leap years. Only in 2100, when, according to the Gregorian calendar, the leap year is omitted, does the complex mechanism require manual correction. However, the