Natural Tanzanite, Emerald, Sapphire & Tourmaline Smooth Oval Hand Polished Oval Beads Strand. Sold per 8 inch strand & Sizes from 7mm to 7mm approx.Tanzanite is an extraordinary gemstone. It occurs in only one place worldwide. Its blue, surrounded by a fine hint of purple, is a wonderful colour. Tanzanite is trichroic and exhibits pronounced pleochroism. The colors respective to the three vibrational directions are sapphire-blue, sage green, and purple.