Opal History, Healing Properties, Types, Uses, & Zodiac Association Opals can be transparent, translucent or opaque and the opals with lots of transparency and clear colors are called crystal opals. Play of color is also one of the unique physical properties of opal. Generally, it is a phenomenon where the stone shimmers and moves with flashes of rainbow colors when it is turned in the light. https://bit.ly/3ZbFwIa #OpalHistory #OpalHealingProperties #OpalTypes #OpalUses