A Date With Destiny: Know Your Calendar Watches

For most watch collectors and enthusiasts, the first encounter with a complication – a feature beyond hours/minutes seconds – comes in the form of a classical jumping date. From that milestone moment, personal tastes, contemporary trends, and budget often steer collectors towards new types of mechanisms, features, and styles.

But there are those who decide to pursue calendar watches as a collection theme. With many styles, display variations, and degrees of complexity, calendar watches hold sway in today’s pre-owned watch market as one of the most popular and practical of all premium watch complications. Unfortunately, complete calendar watches also rank among the most frequently mishandled and misunderstood mechanisms in the hands of otherwise well-meaning owners.

In order to better understand the calendar watch as a class, variations on the type, care and feeding, and buying strategies, watchuwant.com presents an essential guide to understanding complete, annual, and perpetual calendar watches.

According to archaeological records, the Greek “Antikythera mechanism” created between 150 and 100 BC likely represents the earliest example of a comprehensive mechanical calendar, but for practical purposes, the modern triple-date or “complete” calendar wristwatch became practical and popular during the mid 20th century. When a watch features a day, date, and month indication to compliment the time of day, the watch can be described as a complete calendar.

All four watches featured in this article qualify as complete calendars, but they differ in degree of complexity, setting methodology, and in the secondary complications that they incorporate. In all four cases, correct use of the setting devices, understanding handling limits, and an informed purchase process are the keys to long-term enjoyment and retained value. An overview of the watches on hand for this discussion highlights the range of diversity in the universe of calendar watches.

The most complex of these calendars belong to the IWC Portuguese Perpetual Calendar and the Jaeger-LeCoultre Master Grande Memovox. Perpetual calendars require no assistance other than continued mainspring wind in order to maintain track of the date through irregular months, years, and leap years. While there are exceptions, the general rule regarding perpetual calendars holds that the first factory-mandated reset will occur in the year 2100; blame the Gregorian calendar.

Both the IWC and JLC incorporate versions of the IWC perpetual calendar mechanism invented by IWC complication guru Kurt Klaus during the mid 1980s. As sister firms under a common corporate parent, IWC and JLC have tailored the system to suit their unique traditions; note the positions of the subdial indications on the two watches, and it becomes apparent that the same calendar, rotated 180 degrees, features in each. The one distinction stems from the age of the watches; the early 2000s Grande Memovox features the original two-digit year and a 122-year moon phase, and the newer variant in the IWC features four year digits and a moon phase accurate to over 533 years.

Both watches are subject to the most critical limitation by which owners of calendars must abide; the watches feature “danger zones,” or time-spans when the calendars are engaged in changeover. These periods, which extend from late evening to early morning, are vulnerable moments for the calendar drive train. Even changing the time can damage the mechanism, and altering the calendar indications can break the movement. Regardless of whether the calendar is perpetual, annual, or merely complete, this changeover danger zone is a common feature of the genre.

And that brings our study to the second major caveat of calendar watch handling; don’t generalize. The IWC and the JLC feature different danger zones despite their shared mechanical heritage. JLC conveniently illustrates the danger period in red numerals on the watch’s subdial at 6 o’clock (8:30 pm to 3:30am), but IWC expects owners to refer to the user’s manual (8 pm-2 am). Unlike more familiar complications such as chronographs and dual-time watches, perpetual calendars are highly non-standard in their design and operation. That’s certainly the case here, and it pays to sweat the details when dealing with calendar watches.

When shopping for a calendar watch on the pre-owned market, complete sets of technical documents and manuals take on additional importance. The hallmark of a fastidious owner is a clean watch that runs well and includes all accessories. While missing equipment always raises a caution flag, this goes double for calendars. If the previous owner misplaced the documents, that raises questions about how carefully the owner set and maintained the watch. With a simple three-hand watch like a Rolex Submariner, missing accessories devalue the watch. With a calendar – especially a perpetual calendar – missing manuals are a critical warning.

With the exception of systems developed by Ulysse-Nardin, perpetual calendars cannot be reversed, only advanced. As a consequence, it is possible to accidentally advance a perpetual beyond the current date with two undesirable solutions: return the watch to factory service or let the watch stop and wait until real time catches up with the erroneous date. When shopping for a perpetual calendar, make sure the images of the actual watch are available, and ensure that the watch isn’t already suffering “Back to the Future” syndrome. Chosing a seller who uses only actual product photos is critical.

Patek Philippe’s 5960G represented the Geneva institution’s first in-house automatic chronograph movement when it debuted in 2006, but it is the watch’s annual calendar that ensures its relevance to this discussion. Annual calendars, which must be reset on March 1 each year, fall between the complete calendars, which must be reset five times per year, and the perpetuals, which effectively eliminate resetting. Patek opted for an annual rather than perpetual system in order to maintain the targeted sub-$100,000 launch price of the 5960 chronograph-calendar.

Purely in terms of display mechanics and setting mechanism, the Patek differs substantially from the IWC and JLC. Whereas those two employ radial displays for the date and single-point interconnected date advance (turn the crown on the IWC; a dimple-pusher advances the JLC), the Patek uses a window display and three independently adjustable date pushers. While the perpetuals advance all indications at once, the need to make incremental updates to an annual means that a day, date, or month can be cycled without affecting the others. Significantly, this also means that the annual calendar cannot accidentally be advanced irrevocably beyond the current date.

While Patek Philippe specifically indicates that their watch’s three-hand time can be safely advanced through a triple-date change (pm to am), this is not universal to calendar watches. But Patek also emphasizes that the watch’s calendar functions should only be operated while the escapement is running. Look again: there’s a small circular aperture within the subdial of the 5960, and it indicates day (white) and night (black) as a danger zone cue. Other than the practical value of these facts, remember the big-picture takeaway; most manufacturers openly post technical manuals for their watches on their websites. Collectors who find themselves in possession of a watch not accompanied by manuals should leverage this resource, and knowing contents of these instructions arms a buyer with targeted questions when gauging the knowledge of a seller.

Window-style dates offer users the legibility that comes with a simplified display and a limited field of information. While radial indicators feature a mass of days, months, and dates competing for a user’s attention, the window system permits easy reads at a glance. Zenith’s Caliber 410 El-Primero movement has appeared in many variants of its signature chronographs, and the version examined for this discussion has been refined to meet COSC chronometer standards.

As befits a watch designed with precision in mind, the calendar display is engineered to transition completely between indications. While it is normal for a calendar watch to appear “in between” during the changeover process (danger zone hours), it is not normal for the indications to be poorly aligned or stuck between stations during all other periods. Sticky indicators, stiff or immobile date pushers, and incomplete date transitions are the hallmarks of a poorly maintained calendar watch.

Zenith’s system for setting the date is a hybrid of the three watches discussed previously. This Zenith Chronomaster T El-Primero highlights the importance of knowing one’s calendar watch and avoiding generalizations about operation. Like the IWC, this Chronomaster requires the user to pull the crown to the first detent in order to set the date. But while the IWC allows all calendar indications to be set from the crown, Zenith shares the Patek’s separate pushers on the case flank. All of the usual caveats apply to the use of the pushers, but there is one distinction; the Zenith features an independently adjusted moon phase, and this is key.

While the IWC and JLC feature moon phases coordinated with the adjustment of the other date indications, and Patek foregoes the moon phase altogether, Zenith requires the user to think about setting this esoteric indication. Be warned: moon phases also include a danger zone. On many watches, this period overlaps with the conventional date rotation, but some watches employ a mid-afternoon changeover to avoid a massive simultaneous jump from over-stressing the power reserve at night. Owners of calendar watches with manually-adjustable moon phases should make a mental note of this and investigate accordingly.

Above all, seeking and operating a calendar watch should be a rewarding experience. Ideally, history, aesthetics, mechanical interest, and wrist feel should guide the process. In order to align one’s experience as closely as possible with this ideal, it is critical to choose a seller who removes guesswork from assessing condition, operating procedure, and commitment to service if necessary. Look for sellers who regularly sell and service calendar watches. Both of these features are key, because it means that the seller will be poised to understand the handling requirements of calendars and own the means to ensure their integrity before they hit the market. Look for watches with complete technical documentation and for sellers who understand the practical importance of this consideration.

Few watch complications are able to play such a useful role in the daily routines of their owners, and it’s telling that the allure of calendar mechanisms has endured from the time of ancient Greece to the present. When collectors empower themselves with information and buy a seller’s credibility before buying a watch, calendar watches provide enduring pleasure and everyday practicality.