A crystal ball is a crystal or glass ball believed to aid clairvoyance. It is sometimes known as a shew stone. Celtic tribes, known to exist in Britain as early as 2,000 B.C., were unified by a priesthood known as Druids. Druids are one of the earliest known peoples to have used crystal balls in divination. Crystal balls are famously tied to Medieval wizards, psychics, and other spiritual practitioners. Crystal balls are most often used to “see” into the past, present, future by the individual able to see images within the crystal balls surface. Crystal balls comes in all manner of sizes and colors, and are often made with a combination of crystal and glass as pure crystal crystal balls are extremely pricey.