Lightsaber crystals were discovered from some very rare sources in the galaxy. At the top of the list were the Sapith crystals. Every eleven years, the Volice worm of the planet Lwhekk excreted a crystallized material from which Sapith crystals were forged.
Sapith crystals produced an intense lightsaber beam that allowed for increased control over the blade. Sadly, the Volice worm eventually became extinct making Sapith crystals very rare indeed.