Soft, violet-blue hues have made iolite a popular stone. Sometimes mistaken for better-known sapphire or tanzanite, top-color iolite is a rare treat. This gem variety of cordierite shows strong pleochroism. Researchers believe this stone may have been one of the first polarizing lenses. The Vikings may have used this feature to find the Sun on a cloudy day, allowing them to navigate the northern seas.

Today, this gem is rapidly growing in popularity due to its color and affordability. Since iolites have no known color treatments, buyers can be confident their purchases are unenhanced.

Learn more about the quality factors for this trendy stone before your next iolite buying trip.

Iolite Buying and the Four Cs

The IGS iolite value listing has price guidelines for top-color cut stones and cabochons as well as for colorless gems.


Iolite, from the Greek for “violet stone,” is most valuable with a slightly violet-blue face-up color. This hue causes some consumers to confuse iolite with sapphire or tanzanite, two stones of much greater rarity and value. However, most iolite has a washed-out or inky look, and few gems exhibit high saturation. For highly saturated iolite, the ideal tone is medium-dark.