Iolite
Iolite – gemstone
Iolite is a gemstone found in metamorphic and magmatic rocks, as well as in the form of pebbles in alluvial deposits. It is often found in association with andalusite, tourmaline, garnet, quartz, zircon, sapphire, and cordierite. Iolite stones used in jewelry come from secondary deposits. The iolite stone belongs to the group of silicates and is a very rare mineral. The name “iolite” comes from the Greek words “ion” meaning violet, and “lithos” meaning stone. Iolite is also sometimes called cordierite, named after the geologist Louis Cordier, who first studied this mineral. It is believed that iolite is the gemological name for cordierite, used for specimens with a violet-blue color and high transparency. Iolite stones come from Burma, India, Tanzania, the USA, Brazil, Germany, Poland (Lower Silesia), and Madagascar. Like other blue gemstones, it exhibits pleochroic properties. Due to its blue color, iolite is known as “water sapphire” and is sometimes confused with sapphire, topaz, and tanzanite.
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Iolite – Color
It is worth noting that the color of iolite, unlike other blue gemstones, is completely natural. Iolite has a very wide range of colors, including blue, bluish-gray, red, green, yellow, colorless, and brown. However, iolite is most commonly found in blue and purple colors. The blue color of iolite is due to the presence of iron in the mineral; a high iron content results in a dark blue color, while a low amount results in a light blue color. Some iolite stones exhibit optical effects such as asterism, iridescence, and cat’s eye. However, iolite is mainly known for pleochroism, an optical phenomenon where the stone can display different colors depending on the light source and angle. Due to pleochroism, cutting such a stone is not easy because improperly cut stones may lose intensity of color. Faceted cuts (step cut, brilliant cut, and rectangular cut) are mainly used in cutting, highlighting the stone’s beautiful violet color. Cabochon cut is usually suitable for stones showing the cat’s eye effect.
Iolite – Properties
Iolite is considered a gemstone because it meets the requirements by achieving a value of 7 to 7.5 on the Mohs hardness scale. The mineral’s density ranges from 2.53 to 2.66 g/cm3. Iolite stones have a vitreous or greasy luster on their surfaces. Iolite is a magnesium aluminum silicate, so it belongs to the silicate family. It often has a habit of twinned, pseudo-hexagonal prisms. It is characterized by uneven or shell-like fracture and three-directional cleavage, with one direction being particularly distinct. Iolite stones may contain inclusions or growths, but their presence significantly lowers the value of the stone.
Iolite – Price, Significance
Due to its affordable price (compared to other gemstones), iolite is highly valued in jewelry making. It is also a collector’s item. The most valuable iolite stones are those with a very deep blue and purple color. In our online store, you can find faceted iolite stones in round, oval, and octagon shapes. Iolite looks very good in jewelry when combined with other gemstones, so it is often found in rings, earrings, or necklaces alongside diamonds and brilliants.
