Myths, folklore & symbolism
emerald: It is a gemstone that generally shares the symbolism of the color green. The Indians of Central America associated it with blood (among the Indians, the colors green and red are expressions of vital energy), the rain, and the moon. Because of its green color, the emerald is associated in Europe with fertility and thus with moistness, the moon, and spring. In Rome, the emerald was an attribute of Venus.
According to the Book of Revelation, the emerald is among the stones of which the Heavenly Jerusalem is built. In the Middle ages the symbolic content of the emerald was manifold. It was regarded as a potentially effective talisman because it supposedly originally came from hell; it was especially useful against the infernal powers. It was simultaneously believed that placing an emerald on the tongue enabled one to summon evil spirits and to hold conversations with them. To the consecrated emerald (i.e., one freed of its evil powers) was ascribed the capacity to free those imprisoned. In Christian symbolism the emerald signifies purity, belief, and immortality. (Herder)