The Richard Lange Perpetual Calendar Terraluna was the brand’s standout new release of SIHH in 2014, immediately attracting the attention of collectors. It is a superbly complicated timepiece with an instantaneous perpetual calendar and 14 days of power reserve using Lange’s patented, constant force mechanism.

Flip the watch over, and fascinating astronomic complications are found – all embedded within its movement. Three concentric rotating disks made of solid gold poetically represent the earth, moon, and sky’s changing positions. The balance wheel at 5 o’clock represents the sun, and the earth disk completes a 360° rotation once per day, continuously indicating day, night, and time across 24 time zones. Accurate to one day over 1058 years, the outer sky and moon phase disks complete a rotation once per lunar month. When the moon disk is at 5 o’clock, between the sun (balance wheel) and earth disk, it appears dark blue to represent a new moon. The moon disk expands until the disk’s gold portion is fully exposed 14.77 days later upon reaching the 11 o’clock position – an innovative, first of its kind mechanism.

Aesthetically, the watch has a dynamic appeal with regulator-style dial inspired by 19th-century precision clocks, with the minutes by a large central hand, while the Roman hour register is smaller and offset to the right, and constant seconds to the left. The perpetual calendar’s date indication is seen through the Lange’s signature oversized date apertures at 12 o’clock, and the month and day in smaller apertures separated at 4 and 8 o’clock respectively, with a small circular aperture for the leap year indicator at 2 o’clock. The power reserve indication is seen through a discreet aperture found at 6 o’clock.

Consigned by the original owner, the Richard Lange Perpetual Calendar Terraluna offered here is exceptionally well-preserved, and offered complete with box, guarantee, and all original accessories.