Ideal Gem for your collection. Collectors Gem Suitable for gemological Institutions. Among the Rarest of Gemstones. Natural gem Free of any Treatment. 100% Natural - Not treated in any way. Beautiful Center-stone for an engagement Ring. Will make a Gorgeous Ring or Pendent accented with Diamonds. Beautiful sharp Cats eye effect. A Gem of Lasting Beauty. Asterism (or Ray Effect) is best seen in Bright Sunlight or by focusing a Flashlight on the face of the gem. R.I. :1.63-1.64 Hardness :5 Chemical Comp. :Phosphate group Density : 3.17-3.23 Crystal Group :Hexagonal Apatite comes in attractive colors - blue, violet, purple , yellow-green and,blue green. Although a soft material, it is widely used in jewellery due to its bright and attractive colors. Apatite is also very heat sensitive.