This very rare and unusual gemstone was first discovered in 1884 by the Dutch explorer and mineralogist, A.N. Kornerup. Kornerupine has a hardness of 6.5 , and a refractive index of 1.66 to 1.70. This gem is most notable for its distinct pleochrism, that is its change of color from either yellow green to mint green, or purple to green, depending on the direction the material is viewed from. We believe we are the only gem dealer offering this material, as we purchased the entire mine production from 1995 in Tanzania.