Hackmanite Faceted Oval Beads have a vitreous luster with a semi opaque body. The hues range from light lilac purple to a violet hue. This variety of sodalite exhibits a special feature known as tenebrescence that allows the gems to temporarily change color when exposed to different lighting. The gems will fade to grey or white when exposed to sunlight, but the colors will slowly return if stored in the dark for several days or when exposed to shortwave ultraviolet light. Truly a fascinating gemstone that is a rare find! A Quality