How to Build (and Buy) a Leap-Year-Proof Watch
There's little more annoying than looking down at your fine Swiss timepiece and realizing it's wrong. Not a minute fast or slow. Just flat out wrong. If you're going to survive next week's leap day without any horological hitches (or, you know, manually adjusting your watch), you're going to want a perpetual calendar strapped to your wrist. Here's everything you need to know.
Let's start with the basics. A perpetual calendar is a watch that tracks the date and doesn't need to be adjusted for the different lengths of the months or for the leap day every four years. Imagine, not having to fiddle it past the 31 on those shorter months or needing to navigate February separately at all. The only time most perpetuals need adjusting is every 100 years, when we skip a leap year (years ending in "00" are multiples of four, but we don't add a day. Did you even know that?). Most of these timepieces show you the date, day of the week, month, phase of the moon, and even the year within the leap-year cycle.
With the creation of the ref. 5516 perpetual calendar in 1955, Audemars Piguet was the first to put the leap-year cycle right on the dial. Up at 12 o'clock on the face you'll find a register marked "Leap Year | Perp. Cal.," which shows years one through four in the cycle. Now it's pretty much standard to have some kind of subdial like this on a perpetual calendar, if for nothing else than to let the wearer and onlookers know the watch is, in fact, a perpetual watch. (It's obviously not the most useful piece of information on a daily basis.)
The calendar mechanism itself can work in two fundamentally different ways. The traditional way is through a system of gears and springs. As the gears rotate, energy is stored in the springs, and at midnight the energy is let out and the indicators change to the next day/date/etc. This is fine, and it's how most of the more established watchmakers do it, but there are some downsides. Most notably, if you try to adjust the time within an hour or two of midnight, you can permanently damage the movement because of all the extra energy stored in the springs. Also, you usually (there are exceptions) can't move the day/date backward, only forward, when setting the watch. This is the best system, though, if you want everything to switch over instantaneously at midnight with no lag or transition period.
You can also accomplish the same timekeeping functions entirely with gears. It's much harder to engineer, and sure, you can't make the final watch quite as thin, but the system can go in both directions seamlessly, and you don't have to worry about that danger zone around midnight. Brands as diverse as Cartier and Greubel Forsey are starting to adopt this method, and I expect we'll see more perpetuals go this route in the future. Probably the most extreme example of an all-gears perpetual calendar is MB&F's Legacy Machine Perpetual, which uses only gears and has a completely openworked series of dials so you can see all the mechanics at work. For the nerds out there, this is one to behold.
While a lot of great perpetual calendars fit the above criteria, they also usually come with hefty price tags. Look at it this way - a basic Audemars Piguet Royal Oak watch in stainless steel is $17,800. One with a perpetual calendar complication, also in steel, is $60,900. That's more than three times as much. In recent years, however, as young collectors show more and more interest in complicated watches, brands are starting to catch on and are releasing slightly more accessible versions of these holy grail watches. Jaeger-LeCoultre's Master Perpetual Ultra-Thin in stainless steel ($20,400) springs to mind first, as a full perpetual calendar with the entire year shown on the dial and a totally in-house movement. The original silver-dial version was very hard to find, but the newer black-dial version for 2016 should be a little easier to get your hands on. If you're really trying to get a bargain, though, Montblanc is happy to oblige. For just $12,800, you can pick up the steel version of the Meisterstück Heritage Perpetual Calendar, probably one of the best deals in watches today.