Iolite Gemstone Information

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Iolite is a transparent gem-quality form of cordierite, a magnesium iron aluminum cyclosilicate mineral. Although the mineral has a history that dates back hundreds of years, the actual gemstone 'iolite' is considered to be relatively new and lesser-known. Cordierite was officially named after the French geologist, Pierre Louis Antoine Cordier (1777-1861) in 1813. The first significant and exciting discovery of large transparent, gem-quality deposits of iolite was made in 1996 in Palmer Creek, Wyoming (USA) by the American geologist, W. Dan Hausal. The world's largest iolite crystal was discovered south of Palmer Creek, in Grizzly Creek, Wyoming. This record-breaking crystal weighs over 24,000 carats.

The name 'iolite' originates from the Greek word 'ios' meaning 'violet'. Iolite's strong pleochroism earned it the misleading trade name of 'water-sapphire', a name now obsolete. From one direction, iolite can appear sapphire-like blue and from another, it can appear as clear as water. Furthermore, from the top view down, it can appear light golden or honey-yellow in color. 'Dichroite' is another synonym for iolite in reference to its pleochroic ability; 'dichroite' is a Greek word which loosely translates as 'two-colored rock'. Iolite is also known as 'the Viking stone' because according to Norse legend, Vikings used iolite as a polarizing filter to help them find the sun on cloudy days. It is believed that the Vikings discovered iolite deposits throughout Norway and Greenland.

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Iolite deposits can be found in numerous locations around the world. Most of the iolite gemstones available today come from India, but some other significant sources include Australia (Northern Territory), Brazil, Canada (Yellowknife), Madagascar, Myanmar (Burma), Namibia, Sri Lanka (Ceylon), Tanzania and the United States, including Wyoming and Connecticut.

Iolite Color

Iolite is typically light to dark blue and violet, although it can also occur in various shades of yellow, gray, green or brown. The most desirable color is an intense violet blue that can rival that of tanzanite. Iolite is trichroic which means that three different colors can be seen in the same stone depending on the viewing angle. Some lower grade or poorly cut iolite can appear overly dark or 'inky', often appearing near-blackish.

Iolite Clarity and Luster

The mineral cordierite is typically opaque, while fine gem-quality iolite appears transparent to translucent in clarity. In many cases, the cutting quality of the gem can affect its clarity. Stones cut too deep may appear opaque. Most iolite exhibits some visible inclusions, especially in larger stones. Although they are rarely encountered, eye-clean specimens are not unheard of. When polished, iolite exhibits an oily to vitreous luster.

Iolite Cut and Shape

Iolite is frequently given a step-cut to enhance color and it is one of the few gem types that are often intentionally 'windowed' or shallow cut to lighten its tone. Cutters must properly orient the rough carefully, taking into account iolite's trichroism of blue, gray and near colorless forms. The most common shapes for finished stones include traditional faceted rounds, ovals and pear shapes. Fancy shapes and calibrated sizes are relatively accessible.

Iolite Treatment

There are no known treatments or enhancements for iolite, although there is a synthetic cordierite available, which is primarily used for ceramics and other industrial purposes.

Please refer to our Gemstone Glossary for details of gemology-related terms.

Kyanite

Iolite does not have any other closely related gemstones, but there are few varieties of iolite itself. 'Indialite' is a polymorph of iolite which forms under a high temperature and has a very similar chemical structure to beryl. In some rare cases, iolite may exhibit asterism (star) or chatoyancy (cat's eye) when cut en cabochon. Some stones may even exhibit a slight level of aventurescence (metallic glitter) due to disc like inclusions, typically hematite. Hematite-included iolite is sometimes referred to by its trade name of 'bloodshot iolite'.

'Steinheilite' is another term for blue colored iolite, named after Fabian Steinheil, a former Russian Governor-General of Finland. 'Water-sapphire' is a trade name that was once popular but is now no longer used.

Iolite has close mineral associations with sillimanite, spinel, garnet, hematite and plagioclase feldspar. In many cases, iolite may form together with other materials. Alteration products of iolite include mica, talc and chlorite. Iolite can be easily mistaken for other gems such as kyanite, sapphire and tanzanite.

When Leif Eriksson and other legendary Viking explorers ventured out into the Atlantic Ocean, far away from any coastline that could help them determine their nautical position, they had a secret gem weapon - iolite. Viking sailors allegedly used thin pieces of iolite as the world's first polarizing filter. By looking through an iolite lens, they could determine the exact position of the sun on cloudy days to help them navigate safely to their new worlds and back.

Iolite is also said to clear the third eye chakra. It's considered to be a stone of vision, enhancing creative expression. Many believe that it can help recover lost memories and also help induce sleep for those who suffer from insomnia. It is believed that iolite can help those who suffer from eye and vision disorders.

Iolite's hardness of 7 to 7.5 on the Mohs scale makes it quite suitable as a jewelry gemstone. It is hard enough to be worn in everyday rings, but owing to its good cleavage, care should be taken to prevent blows, which could cause fracturing. Iolite is often available in very large cuts, with many stones weighing 5 carats or more. Due to larger cuts being readily available, iolite gems make for excellent fashion jewelry and bold designs. Iolite is an excellent gemstone for pendants, pins, brooches, necklaces and bracelets.

For men, iolite is an excellent 'royal' gem, which is perfect for men's fashion and gemstone jewelry accessories, including cufflinks, iolite rings and tie-tacks. Iolite is an affordable alternative for more expensive blue sapphire or violet-blue tanzanite. Since it is a lesser-known gemstone, most jewelry stores will not have iolite readily available and in stock, so in most cases, iolite will need to be sourced from online suppliers.

Note: Buy colored gemstones by size and not by carat weight. Colored stones vary in size-to-weight ratio. Some stones are larger and others are smaller than diamond by weight in comparison.

Iolite is considered to be fairly hard and durable, but it exhibits good cleavage which adds to its fragility. Extra care should be taken to prevent any hard knocks or blows. It is slightly harder than quartz, but softer than many popular jewelry gemstones (i.e., diamond, ruby and sapphire). It is best to refrain from wearing other types of gemstones together with iolite in order to prevent damage. Iolite should not be cleaned with heat steamers or ultrasonic cleaners. To clean your iolite gems and jewelry, simply use warm soapy water and a soft cloth. Be sure to rinse well to remove any remaining soapy residue. Avoid extreme climates, temperature fluctuations and prolonged exposure to heat and sunlight.

Always remove your gems and jewelry before engaging in any vigorous sports, exercise or household chores. When removing jewelry, do not pull from the stone as this can lead to weakened prongs and eventually a lost stone. Always store gems separately, and if possible, wrap your gems individually using a soft cloth and place them inside a fabric-lined jewelry box for added protection.