ASTERIA or STAR-STONE, a name applied to varieties of ruby and sapphire which exhibit a six-rayed star. Cymophane, or chatoyant chrysoberyl, may also be asteriated. The asterism is due to the reflection of light from twin-lamellae or from fine tubular cavities or thin enclosures definitely arranged in the stone. The astrion of Pliny is believed to have been the modern moonstone.