Tanzanite is the blue and violet variety of the mineral zoisite  discovered in Northern Tanzania in 1967, it is only found in this one small location. Strongly trichroic its colour can vary from blue to violet to burgundy depending on its orientation and different hues can be more apparent under different lighting conditions.   Much material is heated to enhance the blue.   It was named Tanzanite by Tiffany & Co in 1968.