Board Thread:Skyrim/@comment-14027812-20130807032958/@comment-1475805-20140428001206

each soul gem has a tiny pocket dimension that can house a soul. during the quest given by Azura, you were able to go into the dimension space contained within Azura's star. All soul gems probably hold a small pocket dimension and using the soul's power inside the gem would break a soul gem since they are fragile and Azura's star has a better and stronger dimensional structure that can handle the process of taking the souls out. Black soul gem pocket dimensions are tied to the soul cairn and using those gems is actually the process of offering up the souls to the Soul Cairn and the Soul Cairn in return gives power to enchant an object. Regular Soul gems are probably tied to a different dimension. And Azura's star may possibily be tied to Azura's realm of Oblivion. Azura definitely knows a lot about soul gems and how they really work since she was able to take from natural soul gems and artificially create her own perfect soul gem. She may have been the one who caused the Dwemer's disappearance by applying what she knew of soul gems to teach Nerevar how to stop the Dwemer from drawing power from the Heart of Lorkhan and making the heart act as a soul gem and absorb every Dwemer in Mundus.