In KotOR...
It was established that the different colors of the sabers when wielded by the different types of Jedi...
I have not replayed it in some time but I think it went...
Jedi Guardian:
GreenJedi Crusaders:
BlueJedi Sentinel:
YellowThe Sith use an artificial crystal for their light sabers, that gives it the
Red blade.
But I could be wrong...
And from Wookieepedia...
"Lightsabers depicted in the first two released films, A New Hope and Star Wars Episode V: The Empire Strikes Back, had blades that were colored either blue (for the Jedi) or red (for the Sith). This color difference was a decision during post-production when the lightsaber blades were being rotoscoped, as the original blades were simply white. In Star Wars Episode VI: Return of the Jedi, Luke Skywalker's newly-constructed lightsaber was colored blue during the initial editing of the film, and appears so in both an early movie trailer and the official theatrical posters, but in the final film, it was ultimately colored green in order to better stand out against the blue sky of Tatooine in outdoor scenes. It also appeared as green in re-release posters.
Green would become another standard blade color for Jedi lightsabers in the Star Wars prequel trilogy. Mace Windu's amethyst-bladed lightsaber, as first seen in Attack of the Clones, was a personal request from actor Samuel L. Jackson as a way to make his character stand out among other Jedi. Jackson's favorite color is purple and he frequently requests the characters he plays to use an item of the color.
Various blade colors appear in the Expanded Universe and in other Star Wars products. The original Kenner figure of Luke Skywalker in his Tatooine costume from Star Wars was released with a yellow-bladed lightsaber. A multitude of other colors have since been used, including orange, silver, cyan, viridian, gold, bronze, and even black."
