Portugieser Eternal Calendar

The IWC Portugieser Eternal Calendar is a landmark in perpetual calendar watchmaking, debuting as the world’s first wristwatch with a moonphase display that will remain accurate for 45 million years. Developed in Schaffhausen, this model pushes the boundaries of mechanical ingenuity, building on IWC’s legacy of innovative calendar complications. Its introduction marks a new pinnacle within the Portugieser family, appealing to collectors who value both technical mastery and design heritage.

This 44.4mm timepiece houses the in-house caliber 52640, which powers a perpetual calendar with displays for the date, day, month, year, and double moonphase, all programmed to require no manual correction for centuries. The “Eternal Calendar” designation distinguishes it from earlier Portugieser perpetuals, such as the IW5033 and IW5034, by offering an unprecedented degree of accuracy and longevity in its astronomical complication.

Pricing varies with case material—platinum and gold editions command a premium, while dial variants and limited editions can further influence value. When evaluating examples, confirm the presence of original papers and boxes, as these add to collectability. The movement’s complexity makes authorized service history especially valuable, ensuring the calendar’s intricate mechanism remains in optimal condition for future generations.