Iolite is an unusual gemstone that has "pleochroism" meaning it can show different colors when viewed from different directions. Iolite’s strong pleochroism makes it an effective light filter. Early Viking navigators used thin slices of it as a polarizing filter to protect their eyes when looking up into the sun to determine their ship's position. This interesting feature gives gem cutters a challenge; a well cut stone will show as a beautiful blue or blue violet instead of a smoky brown. Cutting orientation will drastically affect body color.Before I knew better, I purchased an Iolite that arrived as a smoky brown. If I held it in a certain direction and I would catch glimpses of a lovely blue. Later, I learned that the problem was the cutter didn't orient it correctly. So, instead of seeing a nice blue violet face up color I only saw a smoky brown. I've never set the stone in a piece of jewelry because it isn't smokey topaz or smokey quartz and the blue flashes are teasing hints of what it might have been. Certainly a "learn by mistake" experience.When Tanzanite was first discovered in 1967 by a Masai tribesman in a remote area of Eastern Africa (Tanzania) gemologists thought it was Cordierite, a well known transparent violet mineral known in the trade as Iolite.Hardness: 7 - 7.5 (Mohs scale) One of the nicest things about Iolite is the fact that it hasn't been "discovered" by savvy marketers. Tanzanite became sought after because it was heavily marketed by Tiffany as an alternate to blue sapphire when the sapphire market's supply had become low and prices as a result skyrocketed. I think you will enjoy a piece of jewelry made with Iolite. It is gorgeous set in gold or silver.