KYANITE 4 MM ROUND CUT ALL NATURAL TOP SAPPHIRE BLUE COLOR CALIBRATED F-1609
Kyanite with its blue color will be lightly included. Top Sapphire Blue Color. INDEX OF REFRACTION: 1.71 - 1.73 HARDNESS: 6.5 - 7.0. A very hard to cut natural gemstone. Sold As A Single Stone. 0.40 Average Carat Weight Per Stone.