The Cartier Pendules Mystérieuse Prism
Carrying on the historical tradition of Cartier, the present "Mystery" desk clock features a transparent window when observing the clock directly. However, from certain angles, the dial and hands mysteriously appear and float in the internal space, allowing one to read the time. This illusion is created by stacking two prisms on top of one another to reflect the dial up into view of the user. This creates the mystery of the piece but also has the quirk of having the dial being reversed when removed from the case.

The legendary relationship between Maurice Coüet (1885-1963) and Louis Cartier at the beginning of the 20th century completed Cartier's reign as the leading firm for jeweled objects. Inspired by popular 19th century French magician and illusionist Jean Eugène Robert-Houdin, Coüet blended exquisite craftsmanship, elegant design and the most technologically advanced mechanisms, resulting in works that continue to entertain and fascinate the observer with their illusion and beauty. Best-known for his 'pendules mystérieuses' or ‘mystery clocks’, the young clockmaker astonished the industry by exploiting the use of illusion. First seen with the ‘Model A’ in 1913, and manufactured exclusively by the Paris branch, the mechanism of mystery clocks is hidden in the frame.

When one looks at the present clock, it is indeed another illusion created by Cartier. Set atop two prisms, the dial is reversed when out of its case. However, when placed atop the prisms, they act like a mirror image and thus it creates a dial that seems to float it its case.

Cartier perpetuated the illusion by fiercely guarding the secret behind these masterpieces, even at the expense of their own sales staff. As Hans Nadelhoffer states in his book Cartier: Jewelers Extraordinary, "It was not simply a matter of the name; the 'mystery clock' contained a secret that was supposed to never be revealed. Over-inquisitive salesmen at the Rue de la Paix, who tried to force explanations from the craftsmen, were rebuffed. The wonder clocks guarded their secret like the Sphinx, and Cartier's protected them from the eyes of prying admirers."

These elegant clocks been the gifts of choice to notables including Queen Mary, who received one in 1924, and Joseph Stalin, who was presented with one by General Charles de Gaulle in 1945. Mystery clocks are considered by many to be one of the House of Cartier’s greatest achievements.

Mystery clocks are described and illustrated in Cartier: Jewelers Extraordinary by Hans Nadelhoffer, pp. 250 - 254 and in The Cartier Collection - Timepieces, Editions Flammarion, pp. 196 - 221.

Another example of this model was sold at Christie's, New York, 21 June 2017, lot 119.