In-Depth: Your Patek Philippe Caliber 89 Now Needs A Service – A Look At Horology’s Easter Problem

When Patek Philippe released the first Caliber 89 (in 1989) to celebrate its 150th anniversary, it was one of the most complicated watches ever made. One of the most unusual complications in the Caliber 89 is one that hasn’t been duplicated since (that I’m aware of, anyway) – an indication for the date of Easter. The reason why is not simply because Patek has a patent for the date-of-Easter mechanism, either. It does, however, have to do with the fact that a true date-of-Easter complication is probably the single most difficult complication in horology – so much so, that despite the Caliber 89, it may, for all intents and purposes, be impossible.

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