Board Thread:Questions and Answers/@comment-7657843-20150504102237/@comment-26281196-20150514212617

For me, only the Aether has shown a secondary (Liquid) form. In Thor's vision at the pool in Age of Ultron, the Tesseract shatters and reveals a blue stone inside it. The Scepter breaks and shows the yellow stone, and the Orb opens to let the purple stone appear. The only one who didn't follow this way is the Aether, who condenses itself before reaching a physical state of red stone

For me, the Tesseract, the Orb and the Scepter are nothing more than containers of energy. If you see the images, you can visibly see the Tesseract as a simple cube made of a glass-like substance with blue energy inside it. For me, the Tesseract and the Scepter were created to extract the powers of the Space and Mind Gems without touching them, and thus, allowing anyone to use them, at the pace that the Orb was created only to imprison the Power Stone with a complex system to let it safe from being used. If you see the Collector's part of GotG, he uses a machine to open the Cube, who reveals to be some sort of complex puzzle to keep the Stone inside it

The Aether is diferent: He is the stone itself, but in another form. Thus, his "hosts" are it's users, and this is why he kills his users and the Tesseract/Scepter not. Probably, it was liquified to slow down the killing process. As we know, the Collector explained that only beings of immense power can wield them. Jane was supposed to die by it but Malekith not. In the start of the movie, is implied that Malekith is powerful, and this is why the Gem accepts him. Jane, obviously, is not, and thus, would die by having it hosted on her

My theory is that the Dark Elvens discovered it's killing properties and liquified it to slow down the process only to find someone who can wield it without dying, or, at least, giving time to the dying user, so he could use it

The Mind and Space showed this two, but instead of finding another way of using it directly, the species in their possession created objects - Tesseract and Scepter - Who can extract their powers without side effects, thus giving security to it's holder as long as him/her didn't touch the Gem

This is what I think