Color: shades of blue to blue-purple Moh's hardness: 7 - 7.5 The
name iolite comes from the Greek 'ios', which means violet.
Iolite is usually a purplish blue when cut properly, the richer
the blue the better. Iolite is a quite hard and durable stone
with a hardness of 7 - 7.5 on the Moh's scale, and the abundant
resources of this gem make it relatively affordable.
Pleochroism, which means 'multicolouredness' is a phenomenon
that is very prominent in iolites and is seen as three different
color shades in the same stone: violet blue, yellow gray and a
light blue. Viking mariners used thin pieces of iolite as the
world's first polarizing filter when they ventured far out into
the Atlantic Ocean, away from any coastline that could help them
determine position. By looking through an iolite lens, they
could determine the exact position of the sun, and navigate
safely to the new world and back. Pleochroism may have been
helpful in navigation but it makes things difficult for a gem
cutter. If iolite is not cut from