1.high purity. 2,high quality 3,best sevice High purity alumina (aluminum oxide), purity, 99.999% Product discriptions ModelVK-L100GCrystalaappearancewhite loose powderAverage particle size ( ... (YAG) and artificial gem. 3, colored gemstones 4, sapphire panel High purity alumina (aluminum oxide), purity, 99.999%