Once used by the Vikings as a compass.
Iolite is often mistaken for Sapphire, and for this reason has been called ‘Water Sapphire’ in the past. The name Iolite comes from the Greek “ion”, which means “violet flower”. Although it had been worn and admired for many centuries, it was only officially named in 1812 by the French geologist P.L.A Cordier (1777 – 1861).
When well cut, Iolite can display a purplish, violet blue and has a tender softness in colour. It can be very similar in colour to that of Tanzanite.
The gemstone is renowned for its pleochroism, whereby different colours can be seen from different directions (as you turn an Iolite, you will see a yellowish blue from one angle, an intense blue from another angle and a light Aquamarine blue to almost colourless from the third angle). What’s more, Iolite cannot be heat treated, so no matter what fascinating colours you find, they are purely the work of Mother Nature. As with many gemstones, the deeper and richer the colour, the better in quality it is considered and therefore demands a higher price.
To take full advantage of its pleochroism, it is crucial that the lapidarist orients the gem properly when cutting. The gem is normally cut into round brilliant cuts, although top-coloured specimens can sometimes be step cut in order to highlight their exceptional colour.
Many legends surrounding Iolite talk of the gem’s ability to strengthen eyesight, some of which possibly originated from its use by Vikings (see below). Iolite is said to enhance curiosity and achievement; many believe it can guide you through spiritual growth. The gem can awaken our thirst for self-love and improve our image of ourselves.
Legendary Viking explorers like Leif Eriksson and others were said to take pieces of Iolite with them to help navigate the open seas of the Atlantic Ocean and beyond.
Due to the gem’s legendary pleochroism, the ship’s navigator would place a piece of Iolite on a pedestal on the ship’s deck. He would then stand behind the gem, staring at it for his entire watch. As the ship veered off-course, the navigator would notice slightly different colours in the Iolite as the sunlight entered the gem through a different axis. He would then call to the helmsman and instruct which way to turn the vessel. For many years it was unknown whether this story was true or just a legend, so various scientists and explorers decided to investigate further. One gemmologist, who also piloted light aircrafts, decided to take a piece of Iolite on a flight to test the theory further. He placed it on top of the dashboard in his cockpit and studied the change of colour as the plane twisted and turned direction. Having witnessed the strength of the pleochroism above the clouds, he was so convinced that the gem could be used as a compass, that on his next flight he covered up the plane’s compass and used nothing more than the Iolite to guide him to his destination. His experiment worked, helping to prove the fact that the Vikings most likely had used the gemstone as the world’s first compass.
It is said that voyages like these also saw the use of the world’s first polarizing filters. When cut thinly, Iolite will act exactly the same as a Polaroid filter on a camera. It has the ability to remove mist and haze and was therefore used by Vikings to accurately pinpoint the sun’s location on a cloudy day. So, even 1000 years ago, this intensely coloured blue gemstone had two totally different navigational purposes.
Non gem-quality Iolite (known as Cordierite) was mined at the Cornish Geevor Tin Mine until the 1990s.
Today Iolite is mined in only a few locations including India, Sri Lanka, Mozambique, Brazil, and Zimbabwe. In Viking times the mining would have probably taken place in Norway and Greenland.