The IWC Portugieser Eternal Calendar
The IWC Portugieser Eternal Calendar
Image: Supplied

A long time ago, in a world far removed from our incarcerating digital calendars, the human obsession with measuring and recording time began. Horology owes its origins to astronomy, beginning with the recording of the cycles of the sun, moon, and stars presented through unique calendars as references for the seasonal planting and harvesting of crops, and to understand life’s order and people’s place in the cosmos.

The Gregorian solar calendar, used today, evolved from these early systems, reconciling some discrepancies and inaccuracies through leap-year adjustments. Traditional lunar calendars such as the Arabic Hijri and lunisolar systems such as the Hebrew and Chinese Xiali account for the moon’s effects.

All this complexity is performed by a mechanical movement inside a wristwatch sometimes just slightly larger than a Roman sestertius. The intricate gear train in a high-complication perpetual calendar keeps accurate timing, accounting for varying month lengths, adding a leap day every fourth year, and often synchronising with a moon-phase display.

Even more phenomenal is the new IWC Eternal Calendar, which sets this in motion for “eternity”, with a moon-phase display so precise it deviates by only one day in 45 million years. Lorenz Brunner heads the research and innovation department at IWC, exploring new materials, movement functionality, and optimisation. It’s here where the new Eternal Calendar was conceived.

“In the beginning, there’s always an idea,” he explained to me during the recent Watches and Wonders fair in Geneva, when asked about his process and the current evolution of the original Kurt Klaus “Operation Eternity” crown-operated perpetual calendar from the 1980s.

“Two separate ideas emerged: one for a secular calendar accounting for all leap years and irregularities, and the other for an extremely precise moon phase. My team and I handled the initial calculations and created the first prototype to ensure all gearing made sense. The calendar is accurate until the year 3999, but our moon phase was off by one day in 577 years. So, we decided to make the moon phase better than our perpetual calendar, combining the two complications. The moon phase is now accurate to one day in 45 million years,” Brunner said proudly.

Design tweaks apply across the entire Portugieser collection for 2024, but the 44.4mm platinum-cased Eternal Calendar features a box-glass-style sapphire on the front and back, allowing full viewing of its movement. While essentially a classic timepiece, the slimmer case and restrained dial design with its numerals and glass sub dials floating above a frosted white lacquered ground give the watch a thoroughly modern feel and make it a practical daily wearer.

Based on the existing IWC manufacture Calibre 52640 with a Pellaton winding system and a seven-day power reserve, the Eternal Calendar required only eight additional components, a remarkable simplification. “Our solution was to implement a secular mechanism and moon phase within the existing space we have, so it’s not a new movement but has new components within the existing gear system, helping us maintain the existing geometry.”

A noticeable trend this year is the focus on high complications, particularly perpetual-calendar watches. What did Brunner think of this? “It’s probably a reaction to the digital, ‘artificial’ world we live in. They offer something real and mechanical. I have three small kids… when I take a watch out of my safe in the morning, they come and ask me to listen to the ‘tick-tock’... Maybe it’s in the genes of human beings that they want to hear the timekeeping, listening to the passing of time.”

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