Crystal ball

A crystal ball is a crystal or glass ball commonly used in fortune-telling. It is generally associated with the performance of clairvoyance and scrying through crystal gazing. Used since Antiquity, crystal balls have had a broad reputation with witchcraft, including modern times with charlatan acts and amusements at circus venues, festivals, etc.

Other names for the object include crystal sphere, orbuculum, scrying ball, shew/show(ing) stone, and more variants by dialect.