Sapphire

Myths, folklore & symbolism
Sapphire: It is a gem regarded in antiquity and the Middle Ages as having healing properties (it was equated with the lapis lazuli). Because of its (usually) blue color, it is a symbol of heaven, heavenly protection, or - for the alchemists - air. In the Apocalypse the sapphire is one of the four foundation stones of the Heavenly Jerusalem. Like all blue stones, the sapphire is regarded in the Orient as a protection against the evil eye. (Herder)