You can find the blue, green, red and yellow crystals in Artifice. We will try to update the guide accordingly. Remember to check out this post on Light saber hilts. Remember that these can change at any time. Here’s a guide to some of the color crystals in the game.
These are fun to collect and some of them can be a real challenge. Star Wars: The Old Republic has many interesting features like the rare crystals that make your lightsaber different colors.