The groundbreaking world timepiece updated in 2019, the Patek Philippe World Time Reference. The 5231J is an almost impossible piece of horological art to buy.
Patek Philippe World Time Reference. New for 2019, the 5231J sits alongside the existing 5231, with a platinum case and matching platinum rice bead bracelet, defining the pinnacle of understated decadence. The 5231J features a yellow gold case of 38.5mm wide and 10.23mm high, slightly smaller than the 39.5mm wide 5231. This is the same case on the 5230 World Chronograph, which is easier to work with because their central dial has a finer guilloche pattern than the enamel. The smaller 38.5mm wide case is preferable, though, as it lacks the inscription "Patek Philippe" on the bezel at 12 o'clock and "Genève" at 6 o'clock. I just don't think contemporary tastes gravitate towards bezel engraving (or well-designed fonts, for that matter).
Several people have correctly pointed out how 5231J is reminiscent of an extremely rare Ref. 2523, introduced in the mid-1950s, perhaps a Patek Philippe World Time watch. Notably, the winglet lugs and polished flat bezel you'll see on this case were introduced in 2016 with the 5230 World Chronograph. This is a big year for world time watches due to changes in global governments such as Moscow. UTC+4 to UTC+3 and a global shift in power resulted in a new city in one time zone (Dubai replacing Riyadh is one of them).
Enamel dial The 5231J features a cloisonné enamel astronomical sphere in the center of the dial. Cloisonne is one of the four enamel processes used by Patek Philippe. The process involves taking a thin gold wire and bending it into the shape of the intended design. The wires are then fastened to the base plate coated with an enamel layer. After the cells formed from the wire are filled with enamel, the process then involves multiple firings, depending on the specific color and effect they are trying to achieve.
The enamel center depicts Europe, Africa and the Americas with a range of greens, browns and yellows, as well as blue representing water. When you see it up close and personal, it's definitely a work of art. In the center of the enamel dial are (rather short) circular hour and toffee hands in 18k yellow gold. As you might guess, using short, polished gold hands on such a rich enamel background hinders legibility. I'd say it's an unfortunate side effect inherent in this watch, but I wouldn't argue with anyone who thinks the circular hour hand is an unforced error.
world time function Along the outer ring are the names of 24 cities, each representing a time zone. At 10 o'clock, you'll see the pushers move the time forward an hour when engaged (the minute hand is unaffected), as well as the city and 24-hour rings. The red arrow at the 12 o'clock position will point to the city corresponding to your time zone. Granted, you don't get the precision increments that would allow a second time zone indicator of 30 or 45 minutes (there are 37 time zones around the world when you consider those), but the ease and elegance of the operation here is world-class.
Let's not kid ourselves: a Patek Philippe World Time watch is one of those things that only Logan Roy from Succession doesn't get knocked down -- though perhaps he'll be more impressed, "It tells you how rich you are at 24 in a time zone, Instead of licking the boots of future son-in-law Tom Wambsgans' surprisingly cringe-worthy line, "It's pretty accurate in telling you how rich you are," when presenting the Patek Philippe.
The 5231J uses a Calibre 240 HU (for all Globeheads, that's the Heure Universelle), which consists of 239 parts, including a 22k gold rotor, and the 240 HU has a power reserve of 48 hours. What’s really remarkable about the 240 HU is that it’s extremely thin, only 3.88mm thick, which is achieved through a patented design that allows the winding rotor to be integrated with the bridge plate. By comparison, the Vacheron Constantin Calibre 2460 WT (there are several, including the Overseas World Time 7700V) is 7.55mm thick and the Jaeger-LeCoultre Calibre 772 (Geophysical Time) is 7.13mm thick. As for the Omega Seamaster Aqua Terra WorldTimer, I'm not quite sure about the thickness of the movement, but I know the case is 15.5mm thick.