Inspired by historical Minerva wristwatches from the 1940s and ‘50s, Montblanc unveils the new Heritage Manufacture Perpetual Calendar Limited Edition 100 featuring vintage aesthetics with a new burnt caramel dial and a fully polished 18 K rose gold case. With its patented Manufacture complication developed internally, this timepiece is one of the most readable with well positioned indications and the possibility of setting the time both forwards and backwards through the crown, allowing the rapid adjustment of one month in under a minute.
With its months lasting 31, 30, or 28 days, and with 29 days in February every fourth year, our Gregorian calendar poses a challenge for watchmakers who have to represent these variations in a mechanical timepiece.
Invented at the end of the 18th century by Thomas Mudge, an English horologist, the perpetual calendar complication is a highly complex mechanism that automatically takes the number of days in the month, and the cycle of leap years, into account. It automatically corrects itself for short months, including the 29th of February in leap years.
As long as it is kept running, the timepiece won’t require any manual adjustment for decades. To achieve this prowess, the functions draw on a technical memory of 1460 days representing four years. Since the early 18th century, the perpetual calendar has not changed much, with a wheel of 48 months managing the four-year periods. The Montblanc perpetual calendar patent is changing that with a complex system made of wheels. Today, the perpetual calendar continues to fascinate watch enthusiasts, making each timepiece highly valuable and truly practical for collectors.
Montblanc Heritage Manufacture Perpetual Calendar Limited Edition 100
Launched two years ago, the perpetual calendar complication took three years to develop due to the complexity of the function. Protected by a patent, the Manufacture calibre MB 29.22 comprises 378 components of which 259 are dedicated to the perpetual calendar function. It is composed solely of wheels and cams, in contrast to most perpetual calendars that use levers.
This mechanism first enables the user to adjust the watch via the crown in both directions (which is not possible with levers). Secondly, thanks to a safety feature, it prevents any setting between the hours of 6 pm and 12 pm, when manipulation could damage the movement.
The perpetual calendar complication is principally made of a central “crown” that drives the entire system with several wheels and three cams with specific rotations that allow the date to jump. The first cam is for the jumping of the date from 28th to 29th (one turn every four years), one is from 29th to 30th (one turn per year), and the last one from 30th to 31st (turns every 31-day month). The cams work independently when there is no modification of the calendar displays when the date changes from 28th to 31th, from 29th to 31st, and from 28th to 31st.
Furthermore, the watch offers an outstanding view on a realistic domed rose gold-coated moonphase surrounded by a starry sky which is extremely precise and only requires adjustment every 122 years. It is combined with a very practical dual-time function with a 24-hour indicator, which is particularly useful when travelling.
Reminiscent of historical Minerva timepieces, the domed lacquered dial is of particular note.
The warm and intense vintage shade of brown has been realized by a special process that takes dexterity and time to achieve. The dial is first produced with two different motifs – a sunray decoration in the centre and a “grainé” finish on the hour ring. After the decoration is added, a Sfumato brown colour is applied to the dial to provide different shades of brown radiating from the centre. It is lighter in the centre and gets darker towards the outside. Several layers of translucent lacquer are then applied to the dial, allowing time to dry between each layer, to enhance the sunray pattern and create a contrasting shine on the final timepieces.
In line with the design codes of the Heritage product line, the watch comes in a 40 mm fully polished 18 K rose gold case with curved horns and is fitted with a sapphire crystal glass box for an elegant vintage look. A brown sfumato alligator strap completes the overall design.