We were wondering the same thing and came across this article from the September 2015 issue of Bloomberg Business. Apparently it can get extremely technical and extremely expensive. Obviously this is a special case and not your typical wristwatch but still a fascinating read.Take a look at the article posted below.
September 17, 2015 — 8:04 AM EDT
Vacheron Constantin Unveils the Most Complicated Watch Ever Made
Some 2,800 components; 57 complications; more than $5 million
We have a new horological king. The Vacheron Constantin Reference 57260 pocket watch is the most complicated mechanical watch ever made.
Watchmakers and their most type-A clients have long chased the title of most complicated watch. Early 20th century industrialists James Packard and Henry Graves Jr. one-upped one another by commissioning extravagant watches, essentially keeping Patek Philippe in business during the lean years between the two World Wars. Last year, Graves's so-called Supercomplication once again became the most expensive watch ever sold, fetching $24 million and topping the $11 million record it set in 1999.
A complication is any watch function that goes beyond showing the hours, minutes, and seconds. How you tally them for the purpose of doling out a "most complicated watch" award might seem pedantic, but additions big (split-seconds chronograph) and small (power reserve indicator) add up—and something that looks like a single feature, such as a perpetual calendar, can technically be counted as multiple complications, because the date, day, and month are each considered to be separate.
By Vacheron's count, the Reference 57260 has 57 distinct complications. This is all packed into a case that is 98 mm (3.86 inches) across and 50.55 mm (1.99 inches) thick. It looks like a pocketwatch, but it isn't fitting in your pants pocket soon. It has a solid 18k white gold case and densely packed components inside. It took a team of three watchmakers more than eight years to design and create the 2,800-component Reference 57260 from scratch.
But enough of the surface-level stuff. Let's count our way to 57.
The front of this watch is the side with the gold Roman numerals up top. Starting with the time, the hours and minutes are shown with regulator-style hands, meaning the hours and minutes are on separate axes (1). These are the wide, curvy blue hands. Looking on the back, you'll see the three-axis tourbillon (2) housing a special spherical balance spring and escapement (3). The small gold hands show a second time zone (4), and there's also a world-time indicator (5) and day/night indicator to show you whether the world time is showing A.M. or P.M. (6). Confused yet? We're just getting started.
There are three (yes, three) full calendar systems in this watch. The first is a standard Gregorian perpetual calendar (7) that includes displays for the date with a retrograde hand (8), day of the week (9), month (10), and year in the leap year cycle (11). There are also indicators for the number of the day of the week (12) and number of the week in the year (13) in accordance with the ISO 8601 standard calendar. You know, just in case.
The second calendar is a Hebrew perpetual calendar (14). This shows the Hebrew name of the day (15), Hebrew name of the month (16), Hebrew date (17), Hebrew secular calendar (18), Hebrew year (19), whether the year has 12 or 13 months (20), where in the 19-year lunar cycle that year is (21), and the date of Jewish holy day Yom Kippur (22), which moves around the calendar.
Finally there's an astronomical calendar, which includes a display of the phases and age of the moon (23), a hand that tracks the movement through the Zodiac along with the equinoxes and solstices (24), a rotating sky chart (25), hands showing both hours and minutes for sidereal time (26-27), and an equation of time indicator for telling the difference between sidereal time and solar time (28). Sidereal time tracks the earth in relation to the stars instead of in relation to the sun—it's used mostly by astronomers and differs from solar time by plus or minus a few minutes, depending on the time of year. You can also see what time the sun will rise (29) and what time it will set (30) in the watch owner's home city as well as how long the day (31) and night (32) will each be on that day. With the three calendars, you're pretty much out of excuses for running late or missing appointments.
Of course there's also a chronograph, and it's one that's a first of its kind. It's a split-seconds chronograph that uses two hands accurate to one-fifth of a second (33-34) to record the seconds, each with its own column wheel for precise activation. These hands are retrograde, meaning they sweep up and back, instead of all the way around the dial. There's also a 60-minute counter (35) and a 12-hour counter with a column wheel (36) for timing longer intervals. All this also sits on the front of the watch.
Completing the grand complication function trio (calendar, chronograph, chiming) are both alarm and time-striking features. There's a single gong and hammer alarm (37) with a strike/silence indicator (38), an alarm-specific power-reserve indicator (39), a system to keep the power from being overwound (40), and a choice of having the alarm strike out the time with the grande or petite sonnerie (41).
You can also strike out the time on demand with the over-the-top carillon system, which simulates the Westminster Cathedral bells using a five-gong and five-hammer system (42). As time passes, you can have it automatically strike the hours and quarter hours with a grande sonnerie (43) or just the quarter hours with a petit sonnerie (44) and also activate a standard minute repeater function for striking the time on demand (45). The customer chose to have a night silencing feature to keep the sonnerie from activating between 10 p.m. and 8 a.m. (46). Two independent indicators let you select the chiming mode and silencing feature (47-48). The alarm is also linked to the carillon system (49), so you can also select to use the carillon chimes as the alarm chime, which also has its own indicator (50).
We're getting close. Now we're in miscellaneous territory. There's a power reserve indicator for the main time-keeping system (51), a second power reserve indicator for the carillon striking system (52), a lock to stop the striking (53), a special winding system to let you power everything up (54), an indicator to show you what the crown is winding or setting (55), a multiposition setting system to aligning the hands (56), and a concealed winding crown just for the alarm (57). Whew. We made it. Fifty-seven it is.
The Reference 57260 was a special commission by a private collector and is not available for sale. At the request of the client, Vacheron Constantin is not disclosing the exact price, though based on the prices of other custom complicated watches, we estimate the collector is parting with upwards of $5 million.