Space Gem

What is it?
The Tesseract. This is first shown in Captain America: The First Avenger and this is later shown in Avengers.

The Owner
The current owner of The Tesseract is Asguard. This was shown in Avengers when Thor got hold of The Tesserant and sent it, him and Loki all to Asguard

Info on The Tesseract
The Tesseract is named for its cube-like appearance, and capable of providing instant access to any location throughout the universe if used correctly, moving any object anywhere through reality. The unique element that composes the Tesseract has also been used to create advanced weaponry by races like the humans and the Chitauri. This stone played an important role in humanity's development during the dawn of the superhero age, attracting the attention of forces such as Red Skull and Thanos, both of whom sought to use the Tesseract's power for their own sinister intern.