"The object of ultimate power and creation, nothing in existence can compare to this divinity of power, pure beauty for it to create something as majestic as you and me" 
— Valkiryon: Protector of Life
Appearance
The Infinity Emerald is a large white diamond cut emerald that glows every single colour every second with a blue, white and black type energy flowing within the emerald.
Powers
The Infinity Emerald's power is eternal and never-ending. The Infinity Emerald has the power to do anything the wielder wishes. although all of it's actions are based off infinity such as the creation of everything which is still infinite creating Universes and Multiverses. Due to the fact it created physics it can easily defy the laws of time, space and reality allowing for absolutely anything to happen. While this is just an object The Infinity Emerald does act like a conscious being which tries to protect itself as shown by creating The Reality Citadel, like it knew that beings might try to abuse it's power.
History
The Infinity Emerald has existed before creation itself and was always there. During an interaction with an unknown force (believed to be impossible, due to nothing being able to exist before reality) The Infinity Emerald unleashed it's power in the form of the Universe which caused The Big Bang and as the Universe's expansion began to halt another form of space continued to expand around the Universe, creating the Multiverse. Soon it's expansion halted and then one final form of space expanded around the Multiverse creating the Omniverse. When this ceased, The Infinity Emerald began producing infinite numbers of Universes and Multiverses of infinite possibilities. Due to it's power of infinity it continued to create many Universes and Multiverses each containing their own Universes which kept replicating and expanding.
During The Big Bang shards of The Infinity Emerald were blasted into the original Universe and eventually landed on Earth, which were lated called the Master Emerald and the Chaos Emeralds but counter to this like anything a negative effect was created in the form of Dark Energy, while as a bonus it may control the rate of expansion, it is comprised with evil and pure darkness.
The Infinity Emerald exists outside of reality within it's own dimension parallel to the Omniverse such as two pieces of paper with one behind the other, the first of which is the Omniverse everything that we know and that we will ever know, the second is The Infinity Emerald's dimensional plain. The Infinity Emerald for some reason created it's own 'home' if you will a type of shell to house it's power in the form of The Reality Citadel, a type of palace floating in the middle of the 2nd dimensional plain it houses and contains The Infinity Emerald's power.