A bicolor tourmaline crystal is a single natural gemstone that displays two distinct colors within the same crystal structure. This stunning optical phenomenon occurs due to subtle environmental and chemical shifts—such as variations in trace elements like iron, manganese, or lithium—while the crystal is actively growing over millions of years.… Common Color Pairings: Pink and green (often referred to as Watermelon Tourmaline if it has a pink core and green rim), blue and green, or yellow and pink. From Afghanistan Weight : 17 grams Sizes : 18x6x5mm 15x5x5mm 14x5x4mm 13x5x4mm 22x2x2mm 15x4x4mm 11x2x2mm 10x4x4mm