Minerals & Gemstone 480x104
Minerals & Gemstone 480x104
Gemstones 160x600

Advertising Information

Pear Iolite with Visible Pleochroism

The Gemstone Iolite

Iolite is the gem variety of the mineral Cordierite. It describes the transparent to translucent form of Cordierite, and it has recently become a popular gemstone. Iolite can be light to deep blue, and usually has a purplish tinge to it. Deeper colored stones are more valuable. Iolite is very affordable and durable, and can be used as a substitute for more expensive blue gemstones such as Sapphire. It is named from the Greek "violet", alluding to the purplish tinge often exhibited by this gemstone.
Chemical Formula Mg2Al4Si5O18
Color Blue, Purple, Gray
Hardness 7 - 7.5
Crystal System Orthorhombic
Refractive Index 1.55 - 1.62
SG 2.6 - 2.7
Transparency Transparent to translucent
Double Refraction -0.01
Luster Vitreous
Cleavage 3,1
Mineral Class Cordierite

Iolite ON EBAY

Iolite is strongly pleochroic, and will exhibit a different color when viewed at different angles. In fact, it is the most pleochroic gemstone, with this effect being clearly noticeable on all transparent Iolite gemstones. A blue or violet-blue Iolite gemstone will become a duller gray or grayish-yellow when viewed at a different angle. For this reason, care must be taken by gemstone cutters to facet Iolite gemstones so that their colors are oriented with the intense blue or violet showing from the top.

Iolite is cut into gemstone facets and cabochons, and is used in all types of jewelry, especially rings, earrings, and pendants.


Iolite gemstones are natural and not treated or enhanced.

Iolite gem deposits are Madagascar, Myanmar (Burma), Sri Lanka (Ceylon), India, and Brazil.

Sapphire - Lacks dichroism, greater hardness.
Kyanite - Rarely transparent, lower hardness, and lacks purplish tinge.
AmethystHas a deeper purple color.

Iolite PHOTOS [Click photos for more details]

Iolite IN THE ROUGH PHOTOS [Click photos for more details]

DISCUSSIONView Forum | Post to Forum
Have a question about Iolite? Visit our Q&A Community and ask the experts!

To sponsor this page, click here.
Let us know how we can update this page
(Click for more details)
We strive for accurate content and locality information. If you feel any of the content is incorrect, or if you feel we are missing vital locality information, please fill out the form below so we can update the site. If you are requesting a locality be added, please only include significant locality occurences for the mineral.