Iolite Gemology
Color-Blue, Violet, Brown, Yellow, Gray
Appearance-Usually transparent
Rarity-Easily obtained
Source-India, Namibia, Australia, Sri Lanka, Mexico, Zimbabwe.
Category-Silicate mineral
Luster-Vitreous
Crystal structure-Orthorhombic, short prism
Mohs scale hardness-7-7.5
Formula-(Mg,Fe)2 Al4Si5O18
This is the best semiprecious gemstone which can be used in place of Blue sapphire. This is cheaper than Blue Sapphire and works efficiently.