Magical mystery tourbillon

In 1912, a young watchmaker named Maurice Couet invented the world's first mystery clock, simply named Model A, for Louis Cartier.

Inspired by the clocks of French illusionist and inventor of modern magic, Jean-Eugène Robert-Houdin, no movement was visible in the transparent clock, the gem-set hands seemingly floating in mid-air.

This was an illusion, of course. While the hands were not connected to any movement, the clock movement was hidden at the base of the clock. The hands were attached to two glass discs - one at the speed of the minute hand and the other at the speed of the hour hand. Completing the illusion was the hour circle that hid the metal borders of the disc.

Later, other models were improved in the spirit of this technology and won loyal - and royal - fans such as the Queen of Spain, Queen Mary wife of King George V and the Maharaja of Patiala. This technique was only ever employed in clocks because of the complication of and delicateness of the moving parts, until Les Mysterieuses de Cartier was unveiled at SIHH this year.

Two of the more aesthetically pleasing and technologically impressive pieces at this year's market, the mystery watches are housed within the Rotonde de Cartier cases.