Kyanite – Natural, Specimen, Blue

Gemstone hardness may vary a bit within a species. However, kyanite is unusual in that its hardness may vary tremendously, from 4 to 7.5, within a single crystal. Faceters rarely cut this stone. Kyanite and quartz, Barra de Salinas, Coronel Murta, Jequitinhonha Valley, Minas Gerais, Brazil. Photo by Géry Parent. Licensed under CC By-ND 2.0.

Article: Gemstone Hardness and Wearability

Credit: Géry Parent