Natural Multi Tourmaline Micro Faceted Fancy Shield Beads Strand Rondelles Sold per 8 inches strand & Sizes from 8mm to 9mm approx.Tourmaline (tur-mah-Leen) is a crystal boron silicate mineral compounded with elements such as aluminium, iron, magnesium, sodium, lithium, or potassium. Tourmaline is classified as a semi-precious stone and the gemstone comes in a wide variety of colors.