Soul gems

Are soul gems a random drop only or can they be found in stores?
Just wondering cos im up too 12th lvl now and I havent found one of them!
Oh and I found a dk blue rhomboid ..supposed to give bonus feat alertness,but no matter what i do it dosent work.

Random drop, plus found at a few merchants, plus there's a guy that randomly appears in random locations that will sell them.

Dark blue rhomboid...I"ll check on this, but if you found it, try activating it's special power to see if it will replace itself with one you can use via the green crystal.

Yeah i tried activating it,dropping it picking up,activating again..green crystal dosent even know its there...never mind i may ask that crafter to combine it into something

i found one of those crystals and after consultating with the dragon he has it sorted.... so keep hold of it till ye see him...