IWC Portuguese Perpetual Calendar

In the early 1980s, IWC’s head-watchmaker Kurt Klaus set out on an engineering journey to translate the Gregorian calendar with its many irregularities into a mechanical program for a wristwatch. His ingenious perpetual calendar took 5 years to design, and debuted in the Da Vinci Perpetual Calendar in 1985. It comprises only about 80 parts and displays the date, day, month, year in four digits, and the moon phase. The smart mechanical program automatically recognises the different length of the months, and even adds a leap day at the end of February every four years. All displays are perfectly synchronised and can be adjusted simply by turning the crown.
The calendar only needs a small adjustment in those centurial years that skip the leap year, which is the case in the years of 2100, 2200, and 2300. Some versions (like this IW502119) even feature a double moon phase display, showing the moon phase on the northern and southern hemispheres.

The moon phase display is so precise that it will deviate from the actual phase of the moon by just one day after 577.5 years.

This IWC Portuguese Perpetual Calendar ref no: IW502119 is enclosed in an 18k rose gold case, measuring 44,2mm in diameter, with a captivating black dial that harmonizes perfectly with a brown alligator strap.

This exceptional timepiece showcases all the functionalities mentioned above, and has only been worn on occasion, since it was completely serviced in 2019.
This timepiece will make a great impression on the wrist,measuring 15.4mm in thickness and with a span of 52.5mm from lug-to-lug.