At 40 millimeters, the Portofino Perpetual Calendar is the smallest perpetual calendar in IWC’s portfolio. This version features an 18-carat 5N gold case, a silver-plated dial, and gold-plated hands and appliques. IWC’s legendary perpetual calendar was originally engineered during the 1980s by the brand’s former head-watchmaker, Kurt Klaus. The ingenious mechanism is mechanically programmed to recognize the different lengths of the months as well as the leap years. It will run without any adjustments until the year 2100.