| We recently found some very fine pieces of iolite | | | | or table of the stone. Iolite's pleochroic properties |
| in the market, not something that happens very | | | | were known to mariners who found practical |
| often. That's because it's rare to find iolite in larger | | | | applications for it. The Vikings reportedly used |
| sizes (over 1 carat) and with good clarity. High | | | | iolite as a polarizing lens, using it to see through |
| quality iolite is a strikingly beautiful stone when cut | | | | the haze and determine the exact location of the |
| well so we wanted to know more about this | | | | sun on overcast days to aid in navigation. |
| unusual gem. Many of the lesser known colored | | | | From the gemological perspective iolite is a |
| gems are lesser known because they are | | | | complex magnesium aluminum silicate with traces |
| relatively soft. This is true of gem varieties like | | | | of ferric/ferrous iron and manganese. The |
| fluorite, apatite, sphene and diopside. But iolite is | | | | magnesium is partially replaced by ferrous iron and |
| actually quite a hard stone, with a rating of 7 to | | | | manganese and the aluminum is partially replaced |
| 7.5 on the Mohs scale, making it as hard as | | | | by ferric iron. Iolite is also known by the mineral |
| tourmaline and harder than tanzanite, peridot and | | | | name cordierite, after Pierre Louis Cordier, the |
| all the quartz varieties. Iolite is not well known | | | | French mineralogist who first described it in 1809. |
| simply because it is so difficult to find. If iolite | | | | The name iolite comes from the Greek ios |
| were commonly available in larger sizes it might | | | | meaning violet. |
| be as popular (and expensive) as tanzanite. | | | | The value of iolite depends on the violet blue |
| Fine iolite is typically a soft violet blue color with | | | | coloration. The richer the blue, the better. Iolite is |
| unusual pleochroic properties, meaning that it | | | | always untreated; in fact there are no known |
| displays different colors when viewed from | | | | treatments to enhance the color or clarity of iolite. |
| different angles. Iolite will display a light blue and | | | | Iolite deposits are found in India, Brazil, Canada, |
| yellow gray in addition to its dominant hue of | | | | Germany, Finland, Madagascar, Mozambique, |
| violet blue. Gem cutters have to be careful to | | | | Burma, Norway, Sri Lanka, Tanzania, the USA, |
| orient the material correctly so that it will display | | | | and Zimbabwe. Most of the fine material we have |
| the violet blue tone when viewed through the top | | | | been seeing recently is from mines in Madagascar. |