Board Thread:Questions and Answers/@comment-7657843-20150502170604/@comment-14267015-20150503185516

I imagine that if someone, like Thanos, got the Aether and could control it long enough, they could transform it back into an actual stone form. The Tesseract might be a bit more difficult if only because we know so little about the material surrounding the Space Stone, but would still be doable if that person had enough strength/power.