The Royal Oak Perpetual Calendar In Platinum, Ref. 25829PT
A high-horology heavyweight.
While there may be some room for debate over whether or not a tourbillon is a complication (as well as how to count the number of complications in a watch, in general) there seems to be no controversy at all about the perpetual calendar. The perpetual calendar is not only universally agreed upon to be a complication, it is one of the three classic high complications which by tradition, goes into making a watch a so-called grand complication (a watch with a repeater, perpetual calendar, and rattrapante).

A perpetual calendar at its simplest, is one which automatically adjusts the date to account for months with 30 or 31 days, as well as the 28 days in the month of February. A perpetual calendar can also add February 29th in a leap year. The very simplest implementation of a perpetual calendar can show just the date, but perpetual calendar watches can also show the day of the week, month, and even where the current date is in the four year Leap Year cycle. The phase of the moon is often added as well.
Perpetual Calendars At Audemars Piguet
Audemars Piguet has been making perpetual calendars for many years. One of the founders, Jules Louis Audemars, made a pocket watch as his “school watch” which ended up as a perpetual calendar, quarter repeater, with deadbeat seconds.. Interestingly enough, while AP made a number of watches with calendar and complete calendar complications, it did not begin making full perpetual calendars until 1950, when the company launched the reference 5516 – this was not only the first perpetual calendar from AP, but also the first perpetual calendar with an indication for the Leap Year.
Since then, AP has produced a wide range of perpetual calendars, with the first – Royal Oak reference 5554 – coming out in 1984. In order to make a Royal Oak Perpetual Calendar, AP starts with the base automatic caliber that powers a simple time-only Royal Oak – specifically, the movement historically found in the Jumbo Royal Oaks, the 2120/21 (which if you’ll recall, was replaced last year for the firm’s 50th anniversary, by the new caliber 7121). The 2120 is an ultra-thin (2.45mm) movement and it was at launch and still is today, the thinnest full-rotor automatic winding movement in the world (although there are thinner micro-and peripheral rotor movements). In order to turn the movement into a perpetual calendar without adding additional height unnecessarily, AP worked with complications and movement specialist Dubois-Dupraz, who in collaboration with AP turned the 2120 into the 2120/2800. Amazingly, the height of the movement increased only very slightly – to just 3.95mm.
The version of the Royal Oak perpetual calendar featured this week, is special on a couple of counts. It is, first of all, cased entirely in platinum, including the integrated bracelet. Platinum is of course, the last word in luxury when it comes to watch cases, and this is only partly thanks to materials costs (in any given year the price by weight for platinum can actually be less than for gold). Instead, the higher cost of platinum – especially in this instance – reflects how much more difficult it is to machine. Specifically, platinum is what machinist sometimes call a “sticky” material – when machined, it has a tendency to adhere to both itself as well as the metal being removed, and the cutting tool, and it dulls machine tools rapidly. I’ve read that it’s possible, using diamond-tipped cutting tools, to machine 100 pieces of jewelry to a level of finish that’s consumer ready. To do the same thing with platinum, you’ll need to replace the cutting head after just 3 pieces.
The Pleasures Of Platinum
Platinum is also an interesting material in terms of its origins. Heavy chemical elements, up to iron, can be formed in the cores of stars as they burn through their hydrogen fuel. Platinum, on the other hand, is so dense that like gold, it can only be formed in the most powerful supernovas, or in the collisions of neutron stars. It is interesting to think that when you look at the placid platinum watch on your wrist, that the material was formed in one of the most violent events in the universe. If the steel Royal Oak justifies its price in part by the difficulty of machining and finishing steel to such a high level, how much more true it is that in platinum, the Royal Oak Perpetual Calendar is an example of the fact that value can be found, not just in what you do, but how difficult it is to do it.
Finally, this version of the Royal Oak Perpetual Calendar 25829PT.OO.0944PT.01 is openworked on both the dial and the movement side. On the movement side, the elaborately pierced and engraved rotor is especially impressive, and on the dial side it is possible to admire the finish on a movement made during a time (this reference was made from 1995 t0 2003) when the highest-end watch brands still took it for granted that they had an absolute obligation to finish their watches as finely as possible. Normally the perpetual calendar works cannot be seen, as they are what watchmakers call “cadrature” (under the dial mechanisms). Here, it’s possible to see the dance of the beautifully finished components every time the date changes (you can have a viewing party for your best watch buddies every four years when the 29th of February switches over).
The Royal Oak is usually described as a revolutionary design, and with good reason, but here it’s especially fascinating for its combination with a traditionally designed, traditionally finished perpetual calendar, featuring a four-year Leap Year indication (a signature detail in AP’s perpetual calendars) and in platinum, to boot – a material whose cosmic origins match the celestial music of the spheres encoded in the perpetual calendar.