Legendary watchmaker Kurt Klaus’ iconic perpetual calendar finds a new, opulent expression in a platinum Portugieser, the go-to IWC model for classical watches.

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.

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Earlier this year, the complication appeared in a Portugieser commemorating IWC’s 150th anniversary in a red gold case available in a limited number of 250 pieces. This new Portugieser perpetual calendar comes in a platinum case, the first time that the classical line, first created for two businessmen from Portugal in 1939, boasts such a combination.

The IWC 52615 perpetual calendar module corrects itself automatically until year 2100. One of its more interesting features is the double moon display that shows the different phases of the moon as viewed from the southern and northern hemispheres. A special reduction gear enhances the precision such that it only deviates from the actual orbit of the earth’s satellite after 577 years. When you consider that, under normal circumstances, the moon’s orbit as indicated on the watch deviates by about 12 seconds in each lunar month, this mechanical ingenuity is pretty cool.

The sapphire caseback offers a chance to admire the decorative beauty of the movement that is also fitted with the Pellaton winding system with ceramic components and an 18k red gold oscillating weight that corroborate to build up a power reserve of seven days.