Bicolour tourmaline is a variety of tourmaline in which a single crystal naturally displays two distinct colors. This happens because the chemical composition of the crystal changes as it grows, causing different trace elements to be incorporated at different stages. Bicolour tourmaline Common color combinations include: * Pink and green (the most famous combination) * Blue and green * Pink and colorless * Yellow and green One especially well-known variety is: * Watermelon tourmaline, which resembles a slice of watermelon with a pink center and green edge…. From Afghanista Weight : 20 grams Average sizes : 17x4x4mm 10x5x5mm 10x3x3mm 13x3x3mm 20x3x2mm 14x4x2mm 13x3x3mm 11x3x3mm