In 1985, IWC Schaffhausen’s watchmaker Kurt Klaus changed the fortunes of his company at the height of the quartz crisis when he successfully realised an automatic perpetual calendar where all the calendar displays – the day, date, month, year and moon phase – can be adjusted with only the crown. Previous perpetual calendars had to be set by multiple pushers. This revolutionary invention first appeared in a Da Vinci watch that also featured a chronograph, and has since become a must-have mainstay in the Swiss manufacture’s perpetual calendar watches, including the new Portugieser.
(Related: Annual Vs. Perpetual Calendars, And Their Finest Examples This Year)