This clear crystal is used for amplifying magic. In it's raw state any magic hitting the crystal will be altered in a random fashion as it passes through similar to light through an irregular shaped crystal. There are a number of similarities between Kyanite and Warpstone.
Once refined it can be shaped to a purpose however it is intrinsically easier to shape the crystals to amplify or alter dark/blood magics than other magics.
It can be used to create a self-recharging invested item.
If tuned to a precise effect, they can increase the magnitude many times over.
Tuned crystals have also been known to have effects such as increasing the rank of the spells in one college.
Kyanite crystals have been used by the Calamar, notably to spread a magical contagion through the Islet der Freiheit.
Untuned crystals are very dangerous, as well as valuable. A 5mm untuned kyanite crystal blew the top off a mountain when an otherwise harmless spell was channeled through it. Another created a pile of rats 10 feet high, and a mile wide. Others had no apparant effect.
These crystals cannot be physically destroyed easily and safely. Crushing them can led to uncontrolled magical events. They can be shattered using resonant frequencies. Some guild members have spent weeks learning 'safe' techniques, which may be of help. If a crystal is untuned, or tuned for evil purposes, it should be destroyed.