Opal, a symbol of hope, has been likened to a rainbow shining through clouds and some people believed that opals were actually bits of rainbow that had fallen to the ground. Others called opal the "cupid stone" and thought it resembled the god of love. When wrapped in a bay leaf, opal was thought to cure eye disease, infections, heart disease, and malignancies. Opal also was believed to prevent conception. When opal glowed brightly, it was suppose to indicate joy and good health. When a person died, it was believed that the opal's fires would be quenched. The gem was sometimes known as the patron stone of thieves, because it was thought to confer invisibility (also when wrapped with bay leaf). Black opals have always been considered particularly lucky and sometimes referred to as the "passion stone." Fire opals were used to attact money.