Produced from 1986 to 2004, the Patek Philippe ref. 3970 perpetual calendar chronograph is one of the defining grand complications of modern Patek Philippe. Its 36mm case houses the manually wound calibre CH 27-70 Q, which combines a chronograph with day, date, month, leap-year cycle, moon phase and 24-hour indication. This example, from around 1990, is crafted in 18k white gold, the most discreet metal of the series. In good condition, it is a highly collectible reference that bridges vintage and modern Patek Philippe watchmaking.
