A perpetual calendar is like a small computer on your wrist.

Think of it this way: Imagine a watch that keeps track of not only the time, but also the date, the day of the week, and the month, tells you whether it’s a leap year or not, and what the current phase of the moon is. Oh, and one more thing — imagine it does all of this mechanically, using springs and gears, and that you only have to adjust it once every century or so. Crazy, right?

Patek Philippe has been making such timepieces since the Second World War, and continues to make some of the most superlative quantieme perpetuelles on the market. This particular example, a Reference 5040P from the 2010s, is a spectacularly elegant model in an offbeat, tonneau-shaped case that remains understated despite its highly complicated nature.

Magnifique! 

Housed in a 39mm platinum case with a signed crown, a sapphire crystal, and a smooth bezel, it features a silver dial with applied, white gold ‘Breguet’ numerals, a matching ‘Breguet’ handset, and an outer ‘railroad’ minute track. Calendar indications include a month and leap-year sundial at 3 o’clock, a date and moonphase aperture at 6 o’clock, and a day and 24-hour sundial at 9 o’clock, all of which is powered by the automatic Patek Philippe Calibre 240 Q. (The magnificent movement architecture, you’ll be delighted to know, is viewable via a transparent sapphire caseback.)

Paired to a signed, black alligator leather strap with a signed, platinum pin buckle, this magnificent QP is a sophisticated masterwork of haute horlogerie — in other words, it’s precisely the type of watch you want from as storied and important a watchmaker as Patek Philippe!