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 : 9 grams Sizes: 23x7x5mm 18x6x6mm 17x8x6mm 15x6x5mm