The one of world Extremely Rare stone, Natural Grandidierite, fine quality facet grade stone
Grandidierite is an extremely rare mineral and gem that was first discovered in 1902 in southern Madagascar.
Mohs scale hardness: 7.5
Optical properties: Biaxial (-)
Crystal system: OrthorhombicB
Crystal class: Dipyramidal
Refractive index: 1.583 – 1.639