Stones and crystals appear throughout the correspondence traditions, assigned to planets, signs, chakras and elements, and used in amulets, talismans and healing practice. Lapidary texts cataloguing the virtues of stones are old and widespread, from Pliny's Natural History and the medieval lapidaries through to the birthstone lists and the crystal lore of the modern New Age.
Each stone is credited with properties (protective, healing, fortunate), and tied by colour, hardness or tradition to a planet, a sign or a chakra, so that it can take its place in the wider web of correspondences.