Genre with Crystal Ball. A crystal ball is a crystal or glass ball commonly used in fortune-telling. In art, a crystal ball is often depicted with a fortune teller or witch gazing into it, symbolizing the search for knowledge of the future or the unseen. Crystal balls can symbolize clarity, truth, and introspection. They may be placed alongside other objects to create a sense of balance or to invite contemplation about the nature of perception and reality. 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. By the fifth century AD, scrying using crystal balls was widespread within the Roman Empire and was condemned by the early Christian Church as heretical. The tomb of Childeric I, a fifth-century king of the Franks, contained a 3.8 cm diameter transparent beryl globe. The object is similar to other globes that were later found in tombs from the Merovingian period in Gaul and the Saxon period in England. Some of these were complete with a frame suggesting an ornamental object. It has been pointed out that these mounts are identical to those of later globes also believed to be used for magic or divination, indicating that these crystal globes may have been used for crystallomancy. John Dee was a noted British mathematician, astronomer, astrologer, geographer, and consultant to Queen Elizabeth I. He devoted much of his life to alchemy, divination, and Hermetic philosophy, of which the use of crystal balls was often included. Crystal gazing was a popular pastime in the Victorian era, and was claimed to work best when the Sun is at its northernmost declination. Immediately before the appearance of a vision, the ball was said to mist up from within. The use of crystal balls for divination also has a long history with the Romani people. Fortune tellers, known as drabardi, traditionally use crystal balls as well as cards to seek knowledge about future events. Main articles: Scrying and Crystal gazing A quartz crystal ball of the type commonly used for divination or scrying The process of scrying often involves the use of crystals, especially crystal balls, in an attempt to predict the future or otherwise divine hidden information. Crystal ball scrying is commonly used to seek supernatural guidance while making difficult decisions in one's life. When the technique of scrying is used with crystals, or any transparent body, it is known as crystallomancy or crystal gazing. Crystal balls are popular props used in mentalism acts by stage magicians. Such routines, in which the performer answers audience questions by means of various ruses, are known as crystal gazing acts. One of the most famous performers of the 20th century, Claude Alexander, was often billed as Alexander the Crystal Seer. Main article: Ball lens Optically, a crystal ball is a ball lens. For typical materials such as quartz and glass, it forms an image of distant objects slightly beyond the surface of the sphere, on the opposite side. Unlike conventional lenses, the image-forming properties are omnidirectional This omnidirectional focusing can cause a crystal ball to act as a burning glass when it is brought into full sunlight. The image of the sun formed by a large crystal ball will burn a hand that is holding it, and can ignite dark-coloured flammable material placed near it.