Tourmaline gem is known as the “gemstone of the rainbow” as tourmaline stones remarkably cover a wide range of colors. Tourmaline can be yellow, blue, green, pink, black, red and sometimes a mixture of two or more colors. Green tourmaline is perhaps the classic color associated to tourmaline. Additionally, tourmaline is the alternative birthstone of October, sharing the month with opal, another gemstone with dazzling display of multicolor. Also, tourmaline is the gemstone of love and friendship.
Tourmaline gems are mixed crystals of aluminum boron silicate with complex and changing composition. Slight changes in the composition cause the gem to change color, hence why single color tourmaline stones are fairly rare to find as the same crystal will often display various colors and shades of the same color. Tourmaline gems with two colors are called bicolor tourmalines, while tourmalines with multiple colors are called multicolored tourmalines. This makes tourmaline an interesting gem, as no two tourmalines are alike.
To categorize the various colors of tourmaline, individual color variety is given their own name in the trade. Red tourmaline is known as rubellite when the ruby red of the gem mentions that color in artificial and daylight. If the red color changes when the light source changes, then tourmaline stone is known as pink tourmaline. Blue tourmaline is known as indigolite and yellow tourmaline, or canary tourmaline, is known as dravite, while black tourmaline is known as schorl. Lastly and most popular, green tourmaline is known as verdelite in the trade, which may contain chrome, know as chrome tourmaline.
Of all the types of tourmalines mined in the world, the most prized and sought after tourmaline stones are those from Paraiba, Brazil and come to be knows as Paraiba tourmaline, or neon tourmaline. These tourmalines have an intense blue to green glow.
Stones with red center and green surroundings are called watermelon tourmaline, which are caused by slices in the crystal. On the other hand, if the gem is colorless and black at the ends, this tourmaline is called a mohrenkopf, named after a popular cake in Germany.
Not only are these very special gems beautiful, tourmaline stones are an interest to science for its physical qualities. Then tourmaline is heated then allowed to cool, tourmaline becomes electrically charged known as pyroelectricity, positive charged at one end and negatively charged on the other end, even after the gemstone is broken into smaller pieces. Additionally, tourmaline can become charged when pressure is applied then removed. These changes to the gem’s polarity will cause the gemstone to oscillate.