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 : 15 grams Sizes: 24x4x4mm 22x5x3mm 13x8x6mm 17x2x2mm 15x5x5mm