Skeleton watch

True 'skeletonization' also includes the trimming away of any non-essential metal on the bridge, plate, wheel train or any other mechanical part of the watch, leaving only a minimalist 'bare' skeleton of the movement required for functionality.

Designs also providing a glimpse of the movement but requiring less modification to the movement itself are the “semi-skeleton” design, with a partial cutaway of the watch face to view the workings of the movement underneath, and the “open heart” design, with a (usually circular) window to view the oscillation of the balance wheel, the “beating heart” of the watch.

The “open heart” design is especially common on watches with a tourbillon complication, the better to show off what is regarded as an example of watchmaking virtuosity.

[2] Patek Phillipe developed skeleton pocket watches for exhibition and display nearly a century later, in the mid-1800s.

[3] Skeleton watches take a lot of time and effort to make, so very few were produced in the 18th and 19th centuries.