Iolite's name comes from the Greek
words ios, meaning "violet,"
and lithos, meaning "stone."
It is also called "cordierite."
When viewed from above, it shows a
blue to violet color, while from the
side it appears nearly colorless or
very light brown. This mysterious
property of showing different colors
in different directions, called "pleochroism,"
is especially strong in iolite. Due
to an appearance that simultaneously
reminds one of the deep blue of sapphire
and the transparency of water, iolite
was long referred to as "water
sapphire." This unique appearance
also makes iolite easy to identify
at a glance among the many blue gemstones.
In their day, the Vikings of northern
Europe apparently used thin slices
of iolite as polarizing lenses, allowing
them to determine the position of
the sun and navigate the seas, regardless
of haze, fog, or clouds. Because of
this, iolite has also been called
"the compass of the Vikings."
When used as jewelry material, only
transparent iolites are faceted, while
translucent ones are cut as cabochons.
Compared to the similarly colored
sapphire, it is a far more affordable
iolite has a distinctive, calm blue
color that should be enjoyed for its
own characteristic beauty, not as
a substitute for gem-quality blue
sapphire. In addition to cabochons,
low-quality material is also used
A majority of blue sapphires are heated
to bring out their beautiful color,
but iolite is a gemstone that is used
in its natural state and never heat-treated.
With a Mohs hardness of 7 to 71/2,
it is harder than quartz and poses
no problems with durability. Currently,
the major sources of iolite are Sri
Lanka, India, Brazil, Tanzania, and
Iolite is a relatively unknown gemstone,
but its beauty and unique character
give it the potential to become a
popular gemstone, if sufficient mining
production can be maintained in the