Only beings of immense power can wield the stones, such as when the Celestials used the Orb to pass judgement on entire planets. Lesser beings are usually unable to grasp the full power of the stones and are destroyed by them when direct contact is made, such as the disintegration of the Red Skull upon holding the Tesseract, the illness of Jane Foster when exposed to the Aether,and the incineration of Carina by the Orb. Only once in recorded history has the power of all six stones been harnessed. This was achieved by six cosmic beings, each with one stone, linking themselves together. The effects were short-lived as the energy of the stones disintegrated all six beings after a few short moments. Despite being referred to as "stones," the Infinity Stones appear in different shapes and states.
The Tesseract is a Space Stone, and one of the most powerful artifacts in the universe. According to Nick Fury, it holds great power that is almost unlimited; Black Widow tells Bruce Banner it has the power to wipe out the entire planet. It can be used to power other weapons; HYDRA's Tesseract-powered weapons were particularly devastating, as a single shot could completely disintegrate an opponent. The device can harness and channel a seemingly unimaginable amount of field quanta to protect itself from being attacked by other energy sources, as seen when the field region, surrounding the Tesseract, proved to be completely impervious to Iron Man's repulsor beams. This prompted Jarvis to state that the cube's barrier is "pure energy", confirmed in one way or another by Loki and Thor on later occasion. The Tesseract was used by Loki to open up a portal to unleash the Chitauri army to devastate New York. Thor used the Tesseract to transport himself and Loki back to Asgard, and after using it to repair the Bifrost Bridge, handed the cube over to Odin.
The Aether is a Reality Stone that existed before the birth of the Nine Realms. It is known to be able to convert matter into dark matter, and otherwise maintains an almost lifelike existence that causes it to bond in a parasitic fashion to a living host. Once bonded, the energies of the Aether slowly consume any mortal host, and also have a volatile and deadly effect on any who come into contact with the host in a manner that the Aether perceives as threatening. Bonded with a stronger host that understands its power, the Aether can be employed as a weapon where it lashes out with a concussive force, or reaches out to convert matter. During its brief time bonded to Malekith, the Aether also enhanced his physical form, causing him to grow threefold in height. After Malekith's defeat, the Asgardians declared that it was unwise to keep two Infinity Stones in the same place, so Sif and Volstagg teleported to Knowhere and turned the Aether over to Taneleer Tivan the Collector.
The Orb is a sphere-shaped vessel that contains a purple-colored gem known as a Power Stone. That Infinity Stone cannot be held by any living being of "insufficient power", or possibly any mortal being. Any living thing that comes into contact with it unable to wield it dies immediately, this includes whole planets. After the defeat of Ronan, the Guardians of the Galaxy handed the Orb over to the Nova Corps.
Although not confirmed yet, the glowing blue-colored crystal located inside Loki's Chitauri sceptre is heavily implied to be the Mind Stone (as demonstrated onto Hawkeye and Dr Erik Selvig at the start of The Avengers). The scepter had a long golden handle and a black fitting which held a blue gem encircled with silver blades. It allowed its owner to open rifts through dimensions with the Tesseract as a gate key, fire destructive blue energy blasts and bend the wills of others. Subjects are placed under control of the scepter by placing the scepter on their chest for a moment, at which time their eyes momentarily turn black, then change to a blue color similar to that of the Tesseract itself, with no visible pupils.
