I recently got excited when I found out that you can get a white lighsaber crystal ingame. A player going by the name of CatchDeathwalker became legendary overnight after posting screenshots of the first white lightsaber ingame. His fame was short-lived when the developers confirmed that he had actually used an exploit to get that color crystal. Looking through history, it looks like CatchDeathwalker had actually found the color exploit in beta and then used it in live. According to the Devs, action has been taken on this idiot's account. If you're going to exploit, or use a known bug to get something that you shouldn't have, it's probably not wise to brag about it in the forums! It's definitely not a good idea to insult the intellect of other players for not being able to work the exploit out. Overnight CatchDeathwalker has gone from legendary to hated in both the SWTOR forums and on Reddit.
Part of the reason why people are so up in arms about colors of crystals is that data mining sites originally posted lots of different color crystals. A whole rainbow variety was available, and every Jedi, myself included, was desperately seeking how to discover these elusive colors. I even know of players who dumped level 40 Republic Jedi Knight avatars for the sole reason of not being able to get a purple lightsaber! Considering that the only purple lightsaber that you see in the movies is Mace Windus, I am surprised that purple is a Sith-only option in SWTOR!
So I have started a list of the different color crystals you can get and how to find or craft them. I will keep updating the list as i find more information and please, if you have any, let me know.