Iolite is a violet-to-blue gem that displays strong pleochroism, meaning it can show different colors when viewed in different directions. Its pleochroic colors differ with its bodycolor. Iolites that appear violet display light violet, dark violet, and yellow-brown. Bluish iolites display colorless to yellow, blue-gray, and dark violet pleochroic colors. Some iolite contains numerous metallic, plate-like inclusions that can cause it to sparkle, an effect called aventurescence. When these inclusions are brownish or reddish in color, the gem might be marketed as “bloodshot” iolite.
Affordable and attractive, iolite can be used in many types of jewelry. It’s sometimes found in large sizes and beautiful, intense colors that satisfy even the most discriminating colored gemstone connoisseur.
Color Iolite possesses two distinctive features—a beautiful, violetish blue through slightly violetish blue hue derived from iron and a striking, eye-visible pleochroism. Its pleochroic colors differ with its bodycolor. Iolites that appear violet display light violet, dark violet, and yellow-brown pleochroic colors. Bluish iolites display colorless to yellow, blue-gray, and dark violet pleochroic colors. From some angles, then, a bluish iolite can actually appear completely colorless or yellow, and a violetish iolite can look brown. Some gems can look grayish or nearly colorless.
Clarity Iolite is commonly transparent, with relatively few inclusions. It can be found in all shapes and has even been carved to beautiful effect.
Iolite can contain inclusions that cause various phenomena. Occasionally, iolites with long, parallel, tubular inclusions are found. When the cut is oriented properly, these stones yield cat’s-eye gems.
Iolite containing numerous metallic, plate-like inclusions can be cut to display a sparkly effect known as aventurescence. When the platelets are brownish or reddish in color, the gem might be marketed as “bloodshot” iolite.
Cut Because it is commonly transparent with relatively few inclusions, iolite is most often faceted. However, iolites can be cut into cabochons or carvings as well. They are frequently seen as beads, especially when the material is of somewhat lower quality.
Carat Weight The size range for a fashioned iolite is anywhere from 1 to 10 carats, but fine iolites over five carats are rare.