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Iolite

· 1 min read · Materials

Iolite is a violet-blue silicate that changes color with the angle (7-7.5 on Mohs); often called “water sapphire” for its look.

Illustration: Iolite

Iolite shows strong pleochroism: it looks violet blue, bluish gray or pale yellow depending on the angle it is viewed from. It is sometimes called “water sapphire”. A legend credits the Vikings with using iolite to navigate.

Properties #

  • Composition: magnesium aluminum silicate (cordierite)
  • Hardness: 7 to 7.5 on the Mohs scale.
  • Color: violet blue; pleochroic.
  • Origins: India, Sri Lanka, Madagascar and Brazil.
  • Treatments: not usually treated.

Uses in jewelry #

  • Rings, earrings and pendants.
  • An affordable alternative to sapphire and tanzanite.
  • Deep-colored jewelry.

Pros and cons #

Advantages #

  • Intense blue at an affordable price.
  • Hard enough for normal use.
  • Cut in large sizes.

Limitations #

  • Its color depends on the cut's angle.
  • Has cleavage and can chip.
  • Less sparkle than other blue gems.

Care and cleaning #

  • Clean with lukewarm water and mild soap.
  • Avoid hard knocks and ultrasonic if fractured.
  • Store apart.

See also #

This entry was drafted with the help of AI and is pending review by the author.