The "Perpetual Calendar," unveiled by Moritz Grossmann at the end of 2025, features an instantaneous calendar advance mechanism utilizing an adjustment lever, representing the ultimate in simplicity and ease of operation.
This platinum model, featuring a rare two-tone dial for Moritz Grossmann, has lance-shaped hands that are finished in the usual blued steel color, presumably for improved legibility. The dial, with its central section lowered in a separate section from the sub-dials, creates a striking three-dimensional effect. It features a manual winding movement (Cal. 101.13) and a platinum case (41mm diameter, 13.9mm thickness). The estimated price is 19,800,000 yen (including tax).
Edited & Text by Hiroyuki Suzuki
[Article published in the July 2026 issue of Kronos Japan]
A new perpetual calendar with refined usability.
To commemorate the brand's 17th anniversary, Moritz Grossmann unveiled the "Perpetual Calendar" at the end of 2025. Similar to the "Date" model released in 2017, it features a bracket-shaped marker date display on the outer edge of the dial, but also incorporates the company's first-ever three-subdial complication. While many images are already circulating online, handling the actual watch reveals a surprising level of three-dimensionality. This is particularly evident in the platinum model with its two-tone dial.
This model features a newly developed perpetual calendar module superimposed on a base movement (Cal. 100 series) with a Grossman winder, representing the second generation of hand-wound movements. The preference for a modular structure rather than integrating the additional mechanisms is characteristic of Jörn Heise, the second chief designer. Hand-wound (Cal. 101.13). 37 jewels. 18,000 vibrations/hour. Power reserve of approximately 42 hours.
The "Cal.101.13" movement, while appearing to be an evolution of the Date (Cal.100.3) based on its external features, is actually a completely new module design. A moon phase display is positioned at 12 o'clock, while both the 3 o'clock and 9 o'clock positions feature coaxial displays combining hands and small windows. The 3 o'clock hand indicates the month, and the small window shows the leap year. The 9 o'clock hand displays the day of the week, and the small window shows the 24-hour day/night indicator. The gear train constituting the perpetual calendar mechanism is extremely simple, but the actual calendar advancement is handled via a shift lever (which serves both advancement and adjustment), resulting in a streamlined overall design. While not as complex as a classic cam-and-lever mechanism, this is also classified as a "discontinuous" mechanism, minimizing momentary swing-downs (maximum of about 15 degrees) by relying on the lever's assistance only at the moment of calendar advancement. Because the shift lever plays the role of what Rolex calls the cam and yoke, or the jumper spring in the ETA system, all the displays that make up the perpetual calendar are instantaneous, just like the date.
2. Sensing points
3. Month display cam
4. 2 year car
5. Month display axis/leap year display axis
6. Vehicles with monthly display switching
7. 31-day vehicle (date vehicle) with snail cam
8. Switch chip
9. Shift lever
10. Day of the week display axis / Day & night display axis
11. Moon phase display switching vehicle
The actual calendar advancement is performed via a switch chip located at the lower end of the shift lever (6 o'clock side). This engagement is controlled by a sensing point at the upper end of the shift lever, which changes the distance the date wheel advances depending on the amount it drops into the month display cam. The minimum is one tooth (= 1 day) and the maximum is four teeth. Furthermore, instead of using a 48-month wheel to count leap years, the design achieves a reduction in parts by using intermediate wheels with a speed increase ratio of 1:2 between the 2-year wheel (= 24-month wheel), the month display cam, and the leap year display (meaning the leap year display disc rotates once every 8 years, not 4 years). While making the movement itself robust is a tradition since the company's founding, the reduction in the number of parts at the design stage is a thoughtful consideration characteristic of the current development chief, Jörn Heise, the second generation to lead the company.
The simplicity of this mechanism is reflected in its actual usability. The main shift lever, which is linked to all calendar displays, is driven via a date wheel with a snail cam (a spring that holds the tip against the snail cam helps to prevent it from swinging down when advancing the calendar), but the tip of the lever other than the date display is divided to allow for individual adjustment. When adjusting the calendar, first set the date with the collector at the 8 o'clock position, then set the month at the 2 o'clock position, the day of the week at the 10 o'clock position, and the moon phase at the 10:30 position. Once adjusted, all calendars will work in conjunction simply by advancing the date.
The fact that the time-setting mechanism and the calendar adjustment mechanism are completely separate is also an advantage in terms of operation. With a perpetual calendar, care must be taken when turning back the clock to avoid crossing midnight (it may even be forbidden in some cases), but with this watch, you probably won't need to be so careful.
This non-continuous perpetual calendar combines robustness achieved through a minimal number of parts with simple operation. While not flashy, it undoubtedly marks a significant milestone in watchmaking history.
