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 : 11 grams Sizes: 18x7x6mm 14x7x7mm 11x9x9mm 12x7x5mm