IWC - the Portuguese Perpetual Calendar

The fascination of an astronomical display

by 25 September 2012

Traditionally, sailing means long voyages, and this means accurate timepieces. IWC are specialists in long calendar periods with its Perpetual Calendar, a truly beautiful movement which, when paired with the brand's Portuguese collection, in existence for over 70 years, creates an enduring classic. (In the photo below, the Portuguese Perpetual Calendar family).

The Portuguese Perpetual Calendar provides a countdown until the next full moon, in reference to the importance of our satellite in dictating high and low tide. It is a beautiful piece with date, day, month and year functions, and a fascinating subdial showing the course of the moon in northern and southern hemispheres. The calendar system advances totally independently, and a manual correction to the date will become necessary only in February 2100. All the owner has to do is to ensure that its 7-day movement remains wound. Another operation that will have to be performed in 2100 is to advance a zero to 1 at the change of the century, in the four-digit year display. Remember to add a clause in your will, providing instructions for your great-grandson!

The lunar display at 12 o'clock has the Earth depicted twice, so that the phases of the moon are shown as seen both in the northern and southern hemisphere. This display is different in the reference 5023, with the moon accompanied by embossed stars, with respect to reference 5021. The accuracy of the lunar display is remarkable, and comparable to scientific instruments. The residual error has been calculated to reach one day's deviation only after 577 years.

The automatic movement has a 7-day power reserve. The white gold case, midnight blue dial, and rhodium-plated moon-phase indicator create a lovely contrast, and ensure effective legibility. The small seconds have the hacking function.

Three versions of reference 5023 are available: a platinum case with silver-colour dial; a red gold case with a silver-colour dial and a red-gold-plated moon on blue background; and a white gold case with rhodium-plated appliqués on a slate-colour dial with sun-pattern finish. The platinum version is made in a limited edition of 250 watches. Price depends on the version: the white gold version with slate-colour dial retails for around $41,100.

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IWC's Pilot's Watches collection