I really do not know which type stone was used for this ring, I can tell you this, the Mystic topaz is a registered trademark and only one company produces this, it is done with a special coating, they use a large varity of clear stones which include, sapphire, topaz, goshenite, quartz, CZ and other clear stones in the process, Azotic Coating Technologies Inc is the sole maker of these and they come in almost 1800 different colors, hope that helps :)