I believe it's a natural fluorite stone. I bought it about 10 years ago at the Sapporo Daimaru department store while traveling. I think I wore it a few times, but I've kept it stored away for a long time. Thank you very much. #MIKIMOTO #TASAKI #TSUTSUMI agete CLASSIC, Ponte Vecchio, Cloche, tatsuo nagahata, Sirena #Azzurro, KAORU, H.P.FRANCE, quarant'otto, MIZUKI, e.m., STAR JEWELRY, k.uno, bizoux, benebene