Iolite is called the "poor man’s sapphire" and "waterblue sapphire" simply because its color often lacks depth and density. The name Iolite comes from "ios" the Greek word for violet. Iolite is a pleochroic gem like its cousins the "Blue Sapphire" and "Tanzanite". Pleochroic means that it transmits light differently when viewed from different directions to the crystal. Only in the case of Iolite, the pleochroism is so acute that it is almost an affliction. Ironically, the Vikings made Iolite pleochroism a virtue by using thin slices of this stone as a light polarizer. Believe it or not, Iolite will do exactly what a camera’s Polaroid filter will do: that is canceling out haze, mist and clouds to make things appear clearer. By observing the sky through Iolite, the Viking navigators were able to observe and locate the exact position of the sun on overcast days. The Vikings in Greenland and Norway mined Iolites at that time. To be more accurate, the Iolite specie is trichroic which means that Iolite exhibits three different colors if viewed from different angles: usually blue, violet or purple, gray or white lavender. As a result of its pleochroic nature, cutting Iolite is extremely difficult. If they are cut slightly off its axis, the color will be faded out or destroyed by showing inky dark blue with no life. If well cut, Iolite can stand out as Top Grade Sapphire or Tanzanite.
HOW TO BUY IOLITE
- Well-cut Gems will have excellent Trichroism and will show off their beauty. Even slightly windowed stones may be accepted as long as the stone is not cut off its axis.
- Stay away of inky blackish color. Sometimes light color Iolite may be more desirable because of their resemblance to Tanzanite.
- If buying an Investment Grade or a collector’s piece, aim for the largest size that you can possibly find. Usually Gems over 5ct sizes are hard to come by.
- Opaque Iolite are not Fine Grades. Look for transparent crystals.
- Flawless Iolites may be common in smaller sizes. However, eye clean stones may be considered Gem Grades if large in size and well cut with excellent color.
Since the recent shortage of Tanzanite supply and the dramatic increase in market price, demand on Iolite has gone far more than expected. In the past two years, the market price has jumped 60 to 75% of what it used to be in the early 1990’s.
As reported by David Federman in his book Consumer Guide to Colored Gemstones, "Stones up to 5 Carats usually don’t command more than $100 per ct in retail stores while the price of sizes between 5 and 10 carats rarely exceeds $150 per CT"
Harder and more affordable than Tanzanite, relative to sapphire with a hardness of q, Iolite with a hardness of 7 to 7 ? is less durable. But relative to Tanzanite with hardness of 6 ?, Iolite is considered more durable. Iolite is never treated, compared to sapphire; Iolite can not be colored lighter.
Usually mined in India, Sri Lanka and Africa, Iolite is a beautiful Gem. Owning an Iolite is a unique experience and a real enjoyment, especially if violet, blue and purple are your favorite colors.
Source: Consumer Guide to Colored Gemstones by David Federman
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