Iolite

The name iolite comes from the Greek ios, which means violet. The Vikings probably mined iolite from deposits in Norway and Greenland. Viking sailors allegedly used ioliteĀ as a polarizing filter to find the sun on cloudy days for a safe offshore navigation.

Iolite is usually a purplish blue when cut properly, with a softness to the color that can be quite attractive. The best color is a lovely violet blue that is unlike other gemstones. Pleochroism is very pronounced in iolite and is seen as three different color shades in the same stone. Depending on the viewing angle, iolite will display violet blue, yellow gray or a light blue.

Its hardness of 7-7.5 makes it a suitable jewelry stone, though the presence of cleavage must be taken into account and some care exercised, like protection from blows.

Iolite colors
Iolite is typically blue, violet or brownish. The best color is a lovely violet blue that is unlike other gemstones. Iolite has different colors in different directions in the crystal. A cube cut from iolite will look a violetish blue almost like sapphire from one side, clear as water from the other, and a honey yellow from the top. This property led some people to call iolite “water sapphire” in the past, a name that is now obsolete.

Buying Iolite
Its hardness of 7-7.5 makes it a suitable jewelry stone, though the presence of cleavage must be taken into account and some care exercised, like protection from blows.

Color
The best color is an intense violet blue that is quite unique. The best specimens can rival fine tanzanite in the saturation of their blue-violet hue.

Lighting
Pleochroism is very pronounced in iolite and is seen as three different color shades in the same stone. In the viewing an iolite stone, the colors violet blue, yellow gray and a light blue can be seen.

Clarity
Though iolite is known as a gemstone of clear vision, larger stones are rarely eye clean.

Cut
Pleochroism makes things difficult for a gem cutter. If iolite is not cut from exactly the right direction, no matter the shape of the rough, its color will not show to its best advantage. Iolite is frequently step cut to enhance color and sometimes windowed or shallow cut to lighten tone. The cutter must orient the rough carefully, taking iolite’s trichroism of blue, gray and near colorless into account.

Iolite location and deposits
Iolite deposits are found in Brazil, India, Madagascar, Myanmar, Sri Lanka and the USA.

Common Iolite treatments
There are no known treatments to enhance iolite.

World-famous Iolite
Iolite hasn’t gained fame as of yet.

Iolite gemology
Species: cordierite
Color: Blue, violet, brownish
Chemical composition: Mg2Al4Si5O18 magnesium aluminum silicate
Crystal system: Orthorhombic, short prisms
Hardness: 7 – 7.5 (Mohs scale)
Specific gravity: 2.58 – 2.66
Refractive index: 1.542 – 1.578
Birefringence: -0.008 to – 0.012
Optical character:
Color of streak: White
Absorption spectrum: 645,593, 585, 535, 492, 456, 436, 426
Fluorescence: None

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

Since those Vikings most probably found the American coastline long before Columbus, iolite achieved a practical importance that easily compensates for the fact, that it produces a blank page in the books of myth, wisdom, the zodiac scheme or the relation between planets and mankind.