Tourmaline round 4mm. Tourmaline comes in a wide variety of colors from brown to black. From green to light blue, from purple to pink. Tourmaline not only is a beautiful stone but also is appreciated for its properties both to physical and mental health of the wearer. This strand of 4mm tourmaline has multicolors of all the colors you can find in a natural tourmaline. Great to use on a multi-strand necklace accented with gold metal spacers.