Despite the occasional continuity error or two, the Marvel Cinematic Universe did a fantastic job of setting up the most ambitious story arc in cinematic history, all built around the concept of what's now known as the Infinity Stones. These powerful ingots contained the accumulated power of all creation on a cosmic level, essentially turning its wielder into a veritable God.
While the MCU did an irable job of adapting the source material into film format, there were still quite a lot of details that never made it in. By understanding how the Infinity Gems from the comics came into being, it's easier to understand the how and why of their adaptation into the films fans know and love so much.
They Are Interdimensional
While the MCU films simplify the origin story of the Infinity Stones by tying them to the Big Bang, the comic book story is much more complex and storied. In those comics, the Infinity Gems were born out of an alternate universe that was inhabited by the Celestials, a race of cosmically powered super-beings that have affected many things in our universe, including the mutant X-Gene.
The MCU does make direct reference to the Celestials, but not of the universe they inhabited. This universe was responsible for the creation of limitless Infinity Gems, which were subsequently deposited into every known parallel universe, effectively seeding them with their power. This origin story has been altered several times throughout the comics, however.
The Nemesis Connection
Originally, the Infinity Gems came about in the comics when the cosmic entity known as Nemesis was unveiled. Originally, she was the only sentient life form in the universe, and rather than deal with the crippling loneliness of her existence, she ended her own life by breaking up her powers into each of the Gems.
Eventually, Nemesis made a return as an Infinity Gauntlet on steroids. As the Gems were an extension of her very being, she could control them better than any other being could ever hope to. Yet, she was still defeated by the Avengers and UltraForce.
They Were Originally All Soul Gems
When the Infinity Gems were first unveiled in the Marvel comic books in 1972, they hadn't yet taken on the form that current fans know so well. In fact, only one, the Soul Gem, was ever unveiled, but that concept evolved a few years later by expanding the number to a grand total of six, all of which were considered "Soul Gems."
Finally, the Gems themselves achieved their full canonical infamy when Thanos entered the picture, and have gone on to evolve more through subsequent material. It all started with one Gem, a generic moniker, and a particularly iconic villain to turn them into a mainstream pop culture name.
The Power Stone
Famously revealed in the first Guardians of the Galaxy film, the Power Stone is responsible for granting the an immense amount of physical power that can boost defensiveness, attack strength, and durability at the cosmic level. It was a key ingredient in Thanos's plan to acquire the other Stones, by effectively supercharging himself.
What the film leaves out is the fact that the Power Stone essentially grants the bearer control over all forms of power and energy that exist at different points throughout space and time. It's not just the collective power of a given moment, but the entire sum of the finite universe. That's a lot of power, indeed.
The Time Stone
Known for its characteristic emerald tint, the Time Stone was actually orange in color in the original comics, and it contained powers beyond just that of temporal manipulation. Yes, the wearer can still operate and control the flow of the past, present, and future, including the ability to travel between them at will.
However, the comic book version of the Time Stone also grants the bearer omniscience, allowing them to see and know everything that was, is, or ever will be. It's the ultimate knowledge usually associated with a God or other deity, and with it comes unfathomable powers of deduction, strategy, and planning.
The Soul Stone
The most mysterious and misunderstood Stones in the MCU is undoubtedly the Soul Stone. It shows up in Avengers: Endgame as the titular Stone that ends up costing Black Widow her life, in exchange for its possession. It seems to have a mind of its own, and that's because it does, in fact.
The stone itself is sentient, but the films leave out a key aspect of its properties, namely a connection to a dimension known as the Soul World. It could theoretically be compared to the Nexus from Star Trek: Generations; a veritable utopia contained inside a pocket dimension that can be accessed via the Stone.
The Reality Stone
The MCU version of the Reality Stone was cleverly hidden in plain sight as a substance known as the Aether, first introduced in Thor: The Dark World. This isn't how the Stone operates in the comics, but it does half-reflect what it's actually capable of. Namely, the ability to manipulate reality and the laws of physics.
Thanos uses this Stone in a variety of inventive ways in the films, but it's based on a facet of its existence talked about in the comics. The Reality Stone is essentially a Genie's bottle capable of granting wishes that transcend the physical boundaries of our universe. It warps and bends reality to the will of whoever wields it.
The Mind Stone
In the MCU films, the Mind Stone is responsible for granting Loki an immense set of powers, including mind control over others via his staff. It's later learned that the staff itself contains the Mind Stone, and it was later used as a catalyst for its fusion with the Ultron AI, creating the entity fans know as Vision.
The comic book version of the Stone was blue, and it went a little further into its capabilities. It significantly boosts the mental acuity and psychic powers of the bearer, allowing them to theoretically probe the minds of every sentient life form in the galaxy. Even Charles Xavier would feel jealous over this amount of power.
The Space Stone
MCU fans know the Space Stone by its more common title, the Tesseract. Inside this glowing blue cube is a Stone capable of immense powers that ended up opening a portal to New York, allowing Thanos's army to swarm in and trigger a fateful conflict that nearly ended in total disaster.
The Stone is purple in the comics, but the effect is the same. It can transport its bearer anywhere across space and time with a thought, which is how Loki used it to escape S.H.I.E.L.D. in Avengers: Endgame. In the comics, the Space Stone allows the bearer to exist simultaneously across all points in time and space, which must take quite a strong mind to both fathom, and control.
No Mention Of The Other Gems
Casual Marvel enthusiasts and fans of the MCU film franchise are relatively well-versed in the Infinity Stones right now, but few may be aware that they aren't the only big rocks on the block. In fact, several other Infinity Gems do exist in the comics and haven't been fleshed out in the MCU at this point.
These are the Ego, Continuity, and Death Gems, each with a completely different set of powers. The Ego Gem serves as the vessel for Nemesis' cosmic consciousness, the Death Gem was fabricated in an attempt to kill Thanos, and the Continuity Gem allowed Deadpool characters to break the fourth wall in an even more hilarious fashion.
