Skeleton watch, it’s a mechanical watches, in which moving parts completely or partially left open, visible through a special window in the dial or the case back. Window can occupy the entire visible area, in the absence of the dial.
This process also involves the removal of excess metal in the details of the movement, there is only light supporting frame, the "skeleton" of the mechanism required for its operation. Often exposed parts of the mechanism are decorated with polishing and engraving.
The first skeleton appeared together with the mechanical clock. The reason for this was not a desire to dhow off the skill, but the difficulty of hiding mechanism in the body. Over time, due to the better arrangement of parts in the mechanism, it was hidden from all sides. However, the back and front cover would lift up to show time. Later crystal would appeared to protect the dial.
The appearance of Skeleton watches as jewelry décor, relates to the XVI-XVII century, when Reformation emerged and spread in Europe. In the 1540s, Jean Calvin, who led the Reformation Protestant movement in France and Switzerland, banned the wearing of jewelry and entertainment. Watch how a utilitarian thing, were not covered by the law and the Geneva jewelers who were on the verge of bankruptcy, along with many talented watchmakers, gathered in Geneva, began to produce skeleton watches artistically decorated with precious stones, enamel and engravings.