Ruusan crystals came from the Mid Rim planet of the same name. While not directly affecting a lightsaber's effectiveness, they aided a Jedi in focusing the Force. Ruusan crystals were lost after the Ruusan Reformation.
- Star Wars: Knights of the Old Republic II: The Sith Lords
- Darth Bane: Path of Destruction
- Star Wars: The Force Unleashed video game
- Star Wars: The Force Unleashed II (Wii Version)