IWC · Quartz

631

Not a mechanical movement, despite the chronograph. The 631 belongs to the Jaeger-LeCoultre 630 family of mechaquartz calibres built for IWC, in which quartz regulates the rate while a conventional mechanical module drives the chronograph, so the counters snap back on reset as a mechanical chronograph does. The 631 adds a moon phase over the base 630. IWC fitted it through the late 1980s and early 1990s to Portofino, Da Vinci and Pilot's chronographs.