Iolite/Cordierite 堇青石

Iolite is a magnesium aluminium silicate and can be quite varied, ranging anywhere from very light blue to deeper blue, usually with a beautiful purplish tinge.

As with almost every other blue gemstone, the deeper the colour, the more valuable iolite is. Iolite crystals are trichroic, which means that three different colours are seen in the same gem, depending on the angle you view it from.