The New Age Source Tumbled Stone Bracelet Black Obsidian Our genuine semi-precious stones elastic bracelet fits most. Black Obsidian Stone is a powerful cleanser of psychic smog created within your aura, and is a strong psychic protection stone. It has powerful metaphysical properties that will shield you against negativity, and their energy may stimulate the gift of prophecy. It an excellent crystal to use when you have been doing spiritual or healing work... as it grounds you to Mother Gaia.