A mystery dial is one in which a disc, often transparent, is used rather than visible hands.
The mystery dial dates to 1839, when magician Jean-Eugène Robert-Houdin created a table clock with a mysterious dial to use in his act. This "mystery clock" inspired inspired the creation of others, including important models from Cartier in the early 1900s. A series of pocket watches was produced beginning in 1888 by Armand Schwob et Frère under the name, Mystérieuse.
The first wrist watch with a mystery dial was the pioneering Juvenia Mystère. First registered in 1945, the Mystère had a transparent case back of crystal, allowing one to peer straight through the outline of the square case. Rather than hands, it used overlapping discs to show hours and minutes.
This became all the rage, with mystery dial watches produced by manufacturers as diverse as Rado and Jaeger-LeCoultre in the 1950s. Early models included the Ebel Videomatic and Titus TV 60. Ernest Borel created the Ernest Borel Cocktail line in 1953, with spirals and patterns on the discs, while Rado created a model with satellites and stars.