In the completed watch, the Chinese perpetual calendar boasts 11 functions and displays the date of the Lunar New Year for the next 20 years on a disk at 6 o’clock on the front dial. To identify the New Year date to 2200 was too much information for just one disk, so the brand made eight more disks, and a house watchmaker will have to change it every 20 years.
The movement also includes a Gregorian perpetual calendar, said to be accurate to 2100, and a Chinese agricultural perpetual calendar, based on a solar calendar that divides the year into 24 solar periods. Together, the three perpetual calendars comprise 20 of the watch’s 63 complications.
Other complications include a split-seconds column-wheel chronograph, which offers two distinct stopwatch operations; six alarm functions; eight chiming functions, including the Westminster carillon played by five hammers and five gongs; nine astronomical complications; and a world time function.
The house said the watch also keeps extremely precise time, thanks to its three-axis tourbillon, a complication that counteracts the effect of gravity on timekeeping accuracy.
“The precision of the three-axis tourbillon regulator has been tested and retested so we can say it has an accuracy of plus or minus two seconds a day, which is unbelievable because it has to drive 2,877 components,” Mr. Selmoni said.
Despite its achievement, Vacheron Constantin has not filed a patent on the Chinese perpetual calendar, saying it doesn’t want to reveal details.
“When applying for patents, it is essential to give a very precise description of the innovation, including technical drawings, as well as to put the invention into perspective in relation to existing solutions,” Mr. Selmoni said. “In other words, you are indeed protecting your invention, yet you are also providing the technical details.”