The Adegan crystal is most commonly known as an Ilum crystal. Used primarily as a focusing crystal for Lightsabers used by both Jedi and Sith. Connected to the force the crystals were faintly detectable by force sensitive individuals. The Galactic Empire banned possession of these crystals and any others that were capable of use in a lightsaber after Executive Order 66 was carried out.
There are five types of Adegan crystals.
Kathracite, Relacite, Danite: These are the most common types of the Adegan Crystal however they did not focus energy well so were usually reserved for training sabers.
Mephite: This is the type most commonly used by Jedi to fabricate their lightsabers.
Pontite: The rarest and almost impossible to find, this crystal has a powerful aura that resonates cooling both skin and tempers.
Adagen crystals are typically Light blue or green but not exclusive to those colors.