Bane's Heart
From Wookieepedia, the Star Wars wiki.
Bane's Heart was a unique carmine lightsaber crystal given to Darth Zannah by her Master, Darth Bane, following the Seventh Battle of Ruusan. She used it in her double-bladed lightsaber.
The lightsaber and crystal later came into the possession of a Dark Jedi murdered by Qymaen jai Sheelal, otherwise known as General Grievous, either on Dica or Necropolis. Sheelal stored the weapon aboard his personal starfighter, which was later recovered by Imperial forces and used as part of the N-K Project. The Bane's Heart lightsaber was used by N-K Necrosis during the Galactic Civil War until he was killed by a group of spacers who took the crystal from his dead body.
When tuned to be used in a lightsaber, it caused that lightsaber to release electrical discharge and made it difficult for anyone other than the rightful owner to use the lightsaber.
[edit] Behind the scenes
Bane's Heart was the second unique lightsaber color crystal available to players in Star Wars Galaxies: An Empire Divided, the first being Sunrider's Destiny. It was added in the 2005 expansion pack Rage of the Wookiees. Its color when used in a player's lightsaber is more along the lines of a purple-red mixture then its otherwise stated color of carmine.
