An open heart dial is has a hole through which the escapement can be viewed.

Revue used the name “Open Heart” on a line of mechanical watches as early as 1979. These featured hand-finished mechanical movements visible through an aperture above the balance. The 1982 line features a circular aperture at the center of the dial.

In 1994, Frederique Constant used the name for their “Heart Beat” model. Since then, the open heart concept and terminology has spread throughout the industry. It is a limited form of skeletonization that focuses on the escape wheel and anchor (the most active parts of the movement) rather than other wheels.

Not all movements are amenable to open heart dials. The escapement must be visible through the top plate, either by design or through skeletonization of the plate. The escapement must also be oriented harmoniously to the overall dial layout, typically between 6 00 and 10 00 on the dial. Furthermore, complications like a date wheel can interfere with visibility so most open heart watches lack these.

• Skeleton
• Openworked
• Dial