Rock crystal is quartz at its clearest — colorless, glassy, optically pure, the “eternal ice” of the ancients and the reference point of the crystal world. Hardness 7; flawless material in large sizes remains satisfying to hold and timeless to wear.Every rock crystal at GEMIC Institute is natural, certified by our Siem Reap laboratory and photographed exactly as offered. Unique pieces; tracked worldwide delivery, 30-day return period.