Eyeball Ruby

"Oh, give it up already! You can't take this away from me! I'm gonna be a legend! I'll go down in history! What will the Diamonds say when they hear that a ruby defeated Rose Quartz? They're gonna give me my own pearl!"

- Eyeball while trying to shatter Steven in "Bubbled"

Ruby-1F4 Cut-4ND, or just Ruby or Eyeball (to Steven) is a Gem and the final antagonist of the 3rd season of Steven Universe. She made her debut at the end of "Barn Mates" and her (potentially) final appearance in the season 3 finale, "Bubbled", where she served as that episode's main antagonist.

Appearance
She has Scarlett skin, the lightest out of all the rubies. Her assemble includes a maroon Homeworld uniform and burgundy shorts. She has big, thick dark burgundy hair and her gem placement replaces her left eye, giving her the nickname Eyeball by Steven.

Personality
Out of all the rubies sent on the mission to retrieve Jasper after failing her mission, Eyeball seems to be the most invested into the mission. At first, she appears to be very stoic and intimidating, but is shown to be polite upon thanking the Crystal Gems for telling them where Jasper is, despite it being a lie. Despite lacking intelligence, like the other rubies, she is the most intelligent of the bunch, being the only one to actually remember where the moon base was. When Amethyst shapeshifted and pretended to be Jasper in "Back to the Moon", Eyeball is shown to have a rather fan-girlish behavior upon meeting her.

History
Eyeball, along with the other rubies, makes her debut at the end of "Barn Mates", where she is seen coming out of her ship with the rest of the rubies. In "Hit The Diamond" She is mostly quiet throughout the episode, only making "grrs" and occasional saying a line. Eyeball, along with the rest of the rubies, were tricked into believing that only humans live at this barn. The Crystal Gems, pretending to be humans, say that they can only search the barn if they win at a game of baseball. After Eyeball with the rest of the rubies realize that they've been tricked, she fuses with them and demands them to tell them where Jasper is, where the Crustal Gems lie and say she's on Neptune. The rubies defuse and head off to Neptune in their ship, where Eyeball thanks them for this.

In "Earthlings", the rubies return, caught by Lapis Lazuli, at the end of the episode. In "Back to the Moon", they are very angered by the Crystal Gems for tricking them into believing Jasper was on Neptune, where as they searched the whole entire solar system searching for her along with it. However, they are tricked once again into believing that Amethyst, who shapeshifted into Jasper, is actually her. Eyeball is the first to great her and is shown to be a rather big admirer of Jasper. When they land on the moon base, Eyeball tells the "captured" Crystal Gems and Amethyst (as Jasper) about the history of Pink Diamond, who was shattered by Rose Quartz during the rebellion, where Eyeball apparently was there to witness it. After Amethyst (as Jasper) gave the rubies a fake mission, Eyeball offers her a ride back to Earth, where she catches Amethyst undisguised. Angered by this, Eyeball and the other rubies fuse to attempt to attack the Crystal Gems, only to be almost instantly unfused when Pearl and Garnet fused into Sardonyx and knocked them into the airlock. The rubies are launched into space, where Eyeball grabs Steven right before she flew away as well.

In Bubbled, Steven bubbles himself upon being launched out of the moon base. Eyeball, however, managed to hang onto Steven's bubble. The two are lost in space, with nothing with them. Eyeball is upset that all of her companions are gone now and has a heated argument with Steven. Ruby at first doesn't believe that the Crystal Gems still existed, but begins to realize so when she realized that Jasper was back on Earth, thinking that Rose still being alive was her only reason in doing so. She reveals that she wanted to see Rose Quartz herself, hoping that 'Jasper' (actually Amethyst) would have some answers. Steven reveals that he basically is Rose and has her gem and shield. Eyeball doesn't believe him at first, but after her gem is cracked while crossing through a meteor field. Eyeball is pulled inside of Steven's bubble, where he uses his healing spit to heal Eyeball. She now believes that Steven is indeed Rose and joyfully laughs with Steven. However, Eyeball then attacks Steven with her Chisel Knife for betraying Homeworld. Eyeball reveals that she wants to be known for being just a basic Ruby who was the one who shattered Rose Quartz once and for all. To save himself, Steven closes his bubble and instantly forms a new one, sending Eyeball to float aimlessly through space.

Trivia

 * Eyeball is the first non-diamond gem antagonist on the show to not of been poofed on-screen.
 * She gained her nickname "Eyeball" from Steven based on her gem positioning being on her left eye.
 * She is the first antagonist gem to become a villain in a later episode, rather than her debut.