Rotonde de Cartier Mystery watch

MYSTERY DISPLAYS, in which the hour and minutes hands seem to rotate in thin air, have been a Cartier specialty for more than a century. This year, the company brought out two new mysterious wristwatches.

One was a tourbillon, the other was this model, called the Rotonde de Cartier Mystery watch. It owes its mystique to four transparent sapphire disks: the hour and minutes hands are each mounted on one, and the other two cover the display on the front and back.

The disks have a nonreflective finish to make them truly invisible. This display module is assembled in a so called “laminar flow hood,” in which air flows continuously, preventing dust particles from settling on the disks.

The movement itself occupies a crescent- shaped zone on the base plate. Although mystery timepieces are usually fragile because of their transparent disks, this one isn’t, according to Cartier.

The watch was tested for shock resistance and was able to resist 500 consecutive impacts, as well as a jolt equivalent to being dropped onto a hard floor from a height of one meter.

The movement is the in-house, hand-wound Caliber 9981 MC, which is 4.61 mm thick and 31.9 mm in diameter. The case is 42 mm in diameter and comes in rose or white gold.