TOP LEFT: A. Lange & Söhne’s Datograph Perpetual watch ($164,800) is crafted in platinum and consists of 556 parts. Accurate to a rate deviation of only one day in 122 years, it is also equipped with chronograph with jumping minute counter, oversize date, day of week and month indication, year and leap year display, moon phase, and day/night indication. Wynn & Company Watches, 702-770-3520.

TOP RIGHT: From Ulysse Nardin, this platinum El Toro GMT +/- Perpetual Calendar watch ($69,900) is created in a limited edition of 500 pieces. It offers dual time function and the UN-32 movement is a COSC-certified chronometer. Highly user-friendly, the watch date, day, month, and year can be instantly changed forward or backward with the + or – pushers when the user changes time zones. Horologio, Grand Canal Shoppes at the Venetian, 702-733-0016.

BOTTOM: The IWC Big Pilot’s Watch Perpetual Calendar Top Gun ($38,600) houses a host of complications, including a perpetual calendar with four-digit year display, moon-phase display in both the northern and southern hemispheres, and offers seven days of power reserve thanks to the Pellaton automatic winding system. It is crafted in titanium and ceramic. Bellusso Jewelers, The Shoppes at the Palazzo, 702-650-2988.

One of the most sought-after complications on today’s watch market—both in vintage and in new timepieces—is the perpetual calendar. These sophisticated time trackers typically hold anywhere from 300 to 600 pieces and command prices that range from $25,000 to hundreds of thousands of dollars, depending on their added functions and adornments. Waiting lists for these watches can run several years—a drop in the bucket, really, since these complex movements can stay accurate for more than a hundred years.

Essentially, the perpetual calendar tracks and displays the day, month, date, and year with automatic accuracy. With the exception of a few that will run for centuries, today’s perpetual calendar watches typically are built to track time until March 1, 2100. At that point in time, the leap year that should occur will be skipped, so the watch will need an adjustment.

The accuracy of A. Lange & Söhne’s Datograph Perpetual watch comes thanks to a spring balance with a frequency of 18,000 semi oscillators per hour.

“To make it as user-friendly as possible, the mechanism needs only to be advanced by one day in 2100 at the push of a button,” says CEO Wilhelm Schmid of A. Lange & Söhne’s perpetual calendar watch. “To make sure that the switching of the calendar indications does not affect the rate of accuracy of the movement, we have devised a way to build up the energy for this process over a period of 24 hours. It is all a very complex process.”

Indeed, perpetual calendar watches house highly complex technical calibers. These movements are composed of date wheels, date-change levers, day wheel, and day-of-the-week lever, as well as an intermediate month wheel with month rack disk and finger that tips the month accordingly at the end to change it to the first of the new month. Some watches also offer year and decade disks, and a moon-phase indicator. The entire labyrinth of disks and levers is linked together, so that every night a switching impulse is transmitted from the main movement of the watch via a tiny lever, pulling on the date-change lever. This impulse causes the date wheel to advance by one position. Simultaneously, the day-of-the-week lever pushes the day wheel, and so on, in turn.

“Perpetual calendars contain complications that are intricate in both mechanics and design while functioning with simplicity and ease,” says Michael Ryan, Wynn’s watch buyer, who names Patek Philippe, Vacheron Constantin, Breguet, Panerai, and Blancpain as top sellers. “They are the most frequently requested complication timepieces we offer because they include all of the elements of time: minute, hour, day, date, month, leap year, and moon phase.”

Certain difficulties arise, of course, in the making of these intricate, labyrinthine timepieces with regard to setting the functions and readouts of the watch. Thus, many of today’s finest watch brands have created unique, patented mechanical systems for setting the dates and times, for unusual readouts, for extended time indication, or for added functions such as chronographs, astronomical indicators, or multiple time zone indicators.

Ulysse Nardin, for instance, holds several patents on its El Toro GMT +/- Perpetual Calendar, which combines the GMT (Greenwich Mean Time) function with the perpetual calendar and adjusts both forward and backward in seconds via the quick-setting corrector on a single crown. Additionally, the hour hand is adjusted instantly with the use of the + and – pushers when the wearer moves between time zones, which gives the watch its reputation as extremely user-friendly. The dial offers a bold, avant-garde display of the multiple functions. Similarly, A. Lange & Söhne’s Datograph Perpetual watch, which consists of 556 parts (including a 48-step perpetual calendar cam), combines a column-wheel chronograph and a fly back jumping 30-minute counter function. This watch is accurately computed to a rate deviation of only one day in 122 years.

One of the more coveted and beautiful readouts on the perpetual calendar watch is the moon-phase indication, which operates via a small disk integrated into the complex movement. As the disk rotates, it reveals the proper moon phase for the progressing month through an aperture on the dial. Some watchmakers adorn the moon-phase disks in enamel, semi-precious stones such as lapis lazuli or onyx, or encrust them in gemstones for stunning beauty. A handful of brands have developed new moon-phase indicators that depict the moon in both the southern and northern hemispheres: IWC’s Big Pilot’s Watch Perpetual Calendar Top Gun boasts, in a circular disk at 12 o’clock, a stunning rendition of two moon phases (one for each hemisphere) for dual drama.

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