|Chemical composition||Complex Mg-Al (magnesium aluminum) silicate|
|Optic nature||Biaxial -|
|Refractive index||1.53 - 1.55|
|Birefringence||0.008 - 0.012|
|Specific gravity||2.58 - 2.74|
Iolite is also named "water sapphire", cordierite or dichroite. Iolite has been worn for centuries and derives its name from “Ios” - the Greek word for violet. Due to it’s strong pleochroism, ancient Vikings used iolite for navigation on cloudy days. The gemstone acted as a polarizing filter and allowed the ancient sailors to determine the position of the sun. The soft blue color makes it a very attractive gemstone. Iolite is the 21st anniversary gemstone.