Bi-colour tourmaline crystals form when the chemical composition of the host fluid changes during growth, resulting in two distinct colours within a single crystal. Popularly sourced from Afghanistan and Brazil, these crystals—often pink and green or blue and green—are highly valued by collectors…. Bicolour tourmaline crystals are natural gemstones that display two distinct colors within a single crystal structure. This rare phenomenon occurs due to subtle environmental changes and shifts in trace chemical concentrations (such as iron, manganese, lithium, or titanium) during the crystal's slow growth process….. From Afghanistan Weight : 11 grams Sizes : 21x5x4 20x7x7 20x9x9