Transparency Natural Tanzanite Faceted Roundle Beads Strand Sold per 20 beads and Size 2mm to 2.5mm 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.