What is Iolite?


Iolite is a transparent, violet-blue, light blue, or yellow-gray mineral. It’s primarily found in Sri Lanka, India, and Madagascar. Iolite is often used as a gemstone and is popular for its pleochroic property, showing different colors when viewed from different angles.

Iolite is a captivating gemstone that comes in shades of violet-blue to light blue. Its unique pleochroic property makes it a popular choice for jewelry like rings and pendants, as it shows different colors depending on the angle of view.

Gemstone Properties

Chemical ClassificationInorganic - Silicate
ColorTypically blue to violet, but can show yellowish-gray or honey color from different angles due to its pleochroism.
TransparencyTransparent to translucent.
OccurrenceIndia, Sri Lanka, and Madagascar.
FormationFormed under high temperature and pressure conditions in regional metamorphic rocks.
CleavagePerfect in one direction
Mohs Hardness7 - 7.5.
Specific GravityApproximately 2.58 - 2.66.
Diagnostic PropertiesPleochroism (different colors when viewed from different angles).
Chemical Composition(Mg,Fe)2Al4Si5O18
PleochroismStrong; shows different colors when viewed from different angles.
Crystal SystemOrthorhombic (variety of Cordierite)
Optical PropertiesBiaxial (-)
Refractive Index1.522 - 1.578
Birefringence0.008 - 0.012
2V angleMeasured: 78° to 82°
Dispersion0.008 - 0.012.