Petro Tourmaline Chips 36″ 4-5mm. These beads are great for multiple strand long necklace. 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. It is one of the most versatile gemstones because of its varied colors and tones. Tourmaline is the alternate birthstone for October.