There are ways to get different color crystals for your weapons. At level 10 I found one way and that is to use the crew skills. I know that you can shop for these color crystals but I seen them when your around level 40 or even level 50. So if you want a different color crystal at level 10 this is the best method. Unfortunately it can only do Green, Blue, and Red at this point. Remember by sending your compaion to that color crystal mission will give you random color crystals and few times the compaion might fail the mission. So keep on trying until you get the color you want. If you are a Jedi class on Tython there is a way to get a yellow color crystal.
How to get Yellow Crystal:
To get the yellow crystal color at like level 7 is to do a quest for the two lovers. If you tell the masters you have found nothing suspicious with Marris and Modern then they will give you the Yellow Crystal. I do not know if any other classes get a different color crystal at a quest or not.
Any other crystals:
The black yellow crystal is the pre-order crystal only.
I'm sure you will get more diffrent color crystals later on like purple, cyan, white, orange etc by doing quests or shop.
Thats about it and I hope this Tutorial helps you.
