These crystals are purchased with Guild Points from the guild that you are signed up with (must have a crafting level of at least 28 in that craft). High-quality crystals are Exclusive so they can't be traded or sold. But you can have more than one (they stack to 12). The only difference between these and the normal crystals you can get from mobs and the Auction House is that high-quality crystals add your name at the bottom of the little display window of the item you make. They don't help you succeed or give a higher chance for a high quality synth.