According to the stuff I've read, the Jedi made the lightsabers from special crysrtals; either blue or green. The Sith also constructed their own lightsabers, but they needed to be made from red crystals. There was also a few lightsabers made from a yellow crytal, but they had the ability to cut though different colored lightsaber beams, and thus they were banned by the Jedi Order. ... God, I'm such a nerd.