A Guiding Light
It is said that iolite dates back to the time of the Vikings, who would use the stone to guide them on their journeys. Using thin slices of iolite could help them determine the exact location of the sun when they were out exploring, helping them travel safely to the new world and back again.
Despite its long history, the gem, valued for its vivid, saturated hues ranging from violet to blue, is still less well-known than stones like tanzanite and sapphires. Difference in popularity from tanzanite “really comes down to quality of color according to Stuart Robertson, research director for Gemworld International, Inc.
Gem cutter at Spectral Gems suggest quality is often an issue when he is looking for Iolite. The gemstone has strong pleochroism--which means different colors can be seen depending on the direction that the gem is turned--making it a tricky stone to cut for the best color.
Interestingly, the deep blue hues of some iolite stones are thought to be caused by the same factors that create the blues in sapphires. Unlike its blue companion, however, iolite can’t be heat treated to help intensify the blue color. Iolites’ low melting point won’t allow for the high temperature needed for the heat treating process according to the GIA.
Prices for Iolite are expected to rise another 10% in the near future. The iolite mines in Africa are small and worked by very small groups of 2 to 12 men. Once the mines reach a certian depth, they can no longer be worked by hand, causing prices to escalate in time.