This year is the first time that a “Calendar” category has been created for the Geneva Watchmaking Grand Prix. Until now, calendar watches were included within the “Grande Complication” category. Among the 12 competing timepieces, seven feature one of the most difficult horological complications to produce: the perpetual calendar. A perpetual calendar movement is capable of recognising 30 and 31-day months as well as leap years, and requires no correction until the year 2100. Why that particular year? Because the Gregorian calendar, instated in 1582 to correct the 0.0078 day/year error generated by the previous Julian calendar, ignores one leap year every 100 years, apart from full centuries when the number of years is divisible by 400.


Richard Lange Perpetual Calendar "Terraluna"
The “Terraluna” by A. Lange & Söhne provides indications on both front and back. On the dial side, the large minutes circle is complemented by the smaller offset hours and seconds counters. No less than five apertures display the brand’s signature outsize date (at 12 o’clock), the day of the week (on the left), the month (on the right), the leap year (numbered from 1 to 4 in red, at 2 o’clock), as well as the power reserve indicated through a slender, elongated aperture at 6 o’clock. A double barrel, coupled with a constant escapement, ensures a 14-day power reserve.

Turning the pink gold case over reveals the biggest innovation of this timepiece: for the very first time on a wristwatch, the orbital moon-phase reproduces the moon’s position in relation to the earth and the sun. On the dark blue celestial disc, studded with over 1,000 sharply contoured stars, the moon orbits around the earth. A round aperture shows the moon phase, while another disc reveals the new and full moons. Meanwhile, the central earth globe spins on its axis once a day and the 24-hour graduated peripheral scale provides a time-of-day reference for the northern hemisphere.

 

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Richard Lange Perpetual Calendar "Terraluna", front and back. © A. Lange & Söhne


Meisterstück Heritage Perpetual Calendar
Montblanc has equipped this perpetual calendar and moon-phase timepiece with the mechanical self-winding MB 29.15 movement providing a 42-hour power reserve. The classically understated 39 mm red gold case frames a silver-toned white dial adorned with a sunburst motif. The date, the day of the week and the month are presented in three identically-sized subdials at 3, 9 and 12 o’clock. The red figure 4 on the month dial indicates the leap year, while the moon-phase aperture reveals a blue sky graced with a yellow moon, and the age of this heavenly body is indicated in days on the upper rim of the dedicated window.

 

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Meisterstück Heritage Perpetual Calendar © Montblanc


Manero ChronoPerpetual
In addition to the usual functions of a perpetual calendar – namely the date, day, month, leap year and moon phases – the Manero ChronoPerpetual comprises a chronograph with flyback function as well as tachymeter scale. To maintain optimal readability, the display of all these indications has been grouped on three counters, meaning that the chronograph counters for the hours (at 6 o’clock) and the minutes (at 9 o’clock) as well as the small running seconds hand (12 o’clock), have been integrated into the calendar displays. The moon phase appears on the right-hand side of the dial in a particularly airy contemporary design, with the silver-toned moon stands out clearly against an anthracite-coloured background. All these indications are driven by a mechanical self-winding Vaucher  movement endowed with a 50-hour power reserve. The 22-carat pink gold oscillating weight may be admired through the integrated sapphire crystal of the 42.55 mm case-back.

 

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Manero ChronoPerpetual © Carl F. Bucherer


Midnight Planetarium
At Van Cleef & Arpels, the calendar is tinged with a sense of poetry. Inspired by the mechanical planetariums produced during the Age of Enlightenment, which already provided an accurate depiction of the movements of celestial bodies, the Midnight Planetarium reproduces the orbit around the sun of its six closest planets – Earth , Mercury, Venus, Mars, Jupiter and Saturn – as well as their position at a given moment. Moreover, each of them also moves in accordance with its real rotation time. While the earth takes 365 days to perform a complete turn around the dial, Saturn will take a full 29 years to do likewise. The watch dial is composed of a set of concentric midnight blue aventurine dials bearing the planets, each made of a different stone.
So how does one actually tell the time on this hand-free watch? All that is required is to observe the position of the shooting star located around the rim of the dial with its 1 to 24-hour graduation. Meanwhile, the day, month and year are displayed on the back of the dial. In a final poetic touch, the Midnight Planetarium also provides a chance to choose one’s lucky day. This fascinating cosmic vision is powered by a 396-component self-winding movement developed in collaboration with Christiaan van der Klaauw.

 

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Poetic Complication Midnight Planétarium © Van Cleef & Arpels