Crystal ball

The crystal ball is a transparent sphere, of rock crystal or glass, used for crystallomancy. Although it has become the quintessential symbol of clairvoyance in popular imagery, only a small number of practitioners ever actually used one. In the sixteenth century, the English mathematician and occultist John Dee was already working with a “shew stone” for his visions. It is set on a stand, in soft light, and gazed at for a long time. Practitioners stress that it is only an aid to concentration and holds nothing in itself.