Originally Posted by Mav
At the moment, I do not know of any way for a Republic player to obtain a Purple Color crystal,
Hm. On obtaining you might be right. Still...
Spoiler (false emperor)
This was the beta but it seems this is a play of a Republic character as a consular type who has somehow managed to snag a violet crystal. May not mean anything, though. So it is possible for a republic character to at least possess one and use it, from what I gather.