Dear Mineral Lovers, We have a special gemstone which is a Tanzanite from Tanzania. This piece is unimaginably rare because change from purple blue to green and semi yellow. This phenomenon is called pleochroism. Quality of this Tanzanite is exceptional. This mineral is by far the best jewelery quality. Stone is perfect terminated from all sides. On one of the side we can see another small grown Tanzanite. That all makes that this specimen is one of the most rarrest collector combinetion form of minerals. Photos on the black graund were made in studio and photos with white graund were made with polarized light. Pleochroism is an optical phenomenon in which a substance has diffrent colors when observed ad different angles especially with polarized light.n form of minerals.