The Space Gem, is one of six Gems that came to be known as the Infinity Gems (previously known as "Soul Gems"), they are some of the most powerful artifacts in the Universe. Each one allows its owner complete omnipotence over one aspect of the universe: time, space, reality, mind, power, and soul. When all six are directly wielded together, nothing is impossible for their bearer.
It is said that the Gems were actually once part of the primordial entity Nemesis, who, eons ago, ended its existence rather than live as the only sentience in the universe. However, the gems were not known to be a collective power for ages. Until, Thanos of Titan assembled the Gems into the Infinity Gauntlet, which exalted him to the position of a Supreme Being.
When used alone the Space Gem enabled its host the ability to teleport anywhere in the Omniverse. The user or someone touching him/her to any place they could picture mentally, or anyone touching the user could picture, even to other dimensions. The Space Gem is believed to have mutated Pip the Troll by it's radiation, he can still teleport anyplace he wishes without leaving a detectable energy trail, even though he is no longer in possession of the Gem. He could teleport mass up to the size and weight of Galactus with ease. After the event known as the Illuminati the Inhuman ruler Black Bolt has taken possession of the Space Gem.