Function

Most of the crystals are kybercrystals used when forging a Lightsaber. Keep in mind that some Kybercrystal Lightsaber colours can only be used by Sith, and others only by Jedi. However, at a high enough level, you can learn a proficiency skill which allows you to bypass this.

Distribution

Star Wars Network mostly follows Legends when it comes to kybercrystals. Instead of bleeding a crystal to obtain a red one (canon), all Lightsaber crystals require a coloured kybercrystal, each equally rare and obtained through the same means. There are some exceptions, like the crystal used for the Darksaber.

Obtainability

Crystals can be obtained in a few ways:

• Completing the Padawan/Apprentice trials as a Jedi/Sith
  When you complete the Padawan or Apprentice trials, depending on whether you're a Jedi on a Sith, you receive a kybercrystal as a reward. Jedi can choose between blue and green, while Sith can only obtain red.

• Crates
  Planetary crates have a small chance of dropping a kybercrystal, although the kybercrystals you can obtain from it depend on the planet. Non-planetary crates, however, can drop all sorts of kybercrystals. As most people will never use a certain kybercrystal, they could be found in the Galactic Trade Network.

• Quests
  Very few quests allow players to obtain a kybercrystal. These quests are usually found on planets such as Tython and Korriban.