In the landscape of 20th-century high watchmaking, Cartier redefined the very concept of a timepiece, transforming it into an object of art, wonder, and mystery. Alongside its famous "mystery" creations, the Parisian Maison introduced an optical masterpiece in 1937: the Prism Clock, born from the genius of master watchmaker Gaston Cusin.

Inspired by the physics of the underwater periscope, the Prism Clock is a tribute to illusion. Thanks to a sophisticated internal system of prisms and mirrors, the clock holds a secret: when viewed from the front, time reveals itself with perfect clarity, reflecting a hidden dial; yet when observed from behind, the object unveils its magic, appearing completely transparent.