“Tourmaline” is the name of a large group of boron silicate minerals. These minerals share a common crystal structure and similar physical properties – but vary tremendously in chemical composition. The wide range of compositions and colour zoning within crystals causes tourmaline to occur in more colours and colour combinations than any other mineral group. Because of this great diversity in colours Tourmaline is so easy to combine. Tourmaline is one of the world’s most popular gemstones and it serves as a birthstone for the month of October.