A specific technique in divination that uses a crystal ball to focus the attention of the “scryer” (the name given to this kind of fortune-teller). A real crystal ball is a polished globe of rock-crystal or clear quartz, but these are costly and most scryers now use a less expensive, commercially available ball of molded glass. Other objects such as polished black mirrors and bowls of water have been used.
The history of scrying is full of recommendations for a great variety of helpful objects. According to John Aubrey, the 17th-century writer, the very best stone to help achieve a psychic state is the “shrew stone,” a smaller and much more expensive version of the crystal ball made of round, cut semi-precious stone beryl, and, he adds, one that is slightly tinged with red.