Mined in the Sigil system, the Sigil crystal was costly but worthwhile due to the searing effect it had once properly placed in a lightsaber. It was a brownish-yellow color in nature, and when used in a lightsaber, the beam produced was incredibly potent and dealt greater damage. The Jedi Nemo had such a crystal; also the Sith Lord Marka Ragnos had one in his possession.