|This article is about the chest gem Ruby. You may be looking for another Ruby.|
Focus, Rubies! This is an important mission from Yellow Diamond, so we can't mess it up.
|—"Hit the Diamond"|
Ruby, nicknamed "Doc" by Steven, is a Homeworld Gem who made her debut in "Hit the Diamond". She is the leader of the Ruby troops sent by Yellow Diamond to retrieve Jasper. She was last seen floating in space after Steven opened the airlock on the Moon Base.
"Doc"'s complexion is the same as the Crystal Gem Ruby's in color, but she wears a yellow transparent visor similar to Peridot's and a pair of red shorts, held on by a pair of black suspenders that have two halves of a yellow diamond on the edges. Her gemstone is located on her chest.
"Doc" is a natural leader, assertive and professional in her actions. While the others are often distracted, she stays on task. She is one of the most competent members of the group along with "Eyeball", who is more experienced in Gem history, due to being older than her. She uses strict and commanding language when interacting with the other Rubies, but is very respectful towards Amethyst, as she thought she was Jasper.
Like the other Rubies, "Doc" is easily fooled by disguises or lies. She also made the error of not including herself in counting the group when she noticed too many Rubies standing about.
"Doc" and her squad of Rubies prepare to search for Jasper after arriving on Earth. They notice a nearby barn and decide to search it. Steven is able to fool them, however, convincing them that they need to win a game of baseball before they can check the barn. The Ruby squad and the Crystal Gem Ruby constitute the Ruby team. They face off against the human team: Steven, Pearl, Amethyst, Lapis, and Sapphire. "Doc" plays as the pitcher for the Rubies. They are able to take the lead in the top of the ninth, but ultimately lose when Sapphire hits a two-run home run in the second half of the inning. When Sapphire reaches the home plate, she accidentally fuses with Ruby, revealing themselves to be Gems. The Homeworld Rubies realize they have been deceived and fuse together. Peridot runs out of the barn to help the other Crystal Gems. Upon learning that she was assigned to the Earth mission, the Ruby fusion demands that Peridot tell her where Jasper is. Steven tells her that Jasper is on Neptune, convincing the Rubies and prompting them to defuse. They board their Roaming Eye and head to Neptune.
"Doc" and her Ruby squad return to Earth. After arriving, the Rubies are imprisoned in water bubbles by Lapis.
The Rubies are released from their water bubbles and questioned by Steven. He asks them why they have returned, and "Doc" reveals to the Crystal Gems that they have realized they have been deceived again, being unable to find Jasper after searching for her on Neptune and all the other planets in the solar system. She angrily demands that they tell her where Jasper is. The Rubies are tricked again, however, when they take Amethyst for Jasper after she had shape-shifted into the Homeworld Gem. "Doc" informs her that Yellow Diamond is awaiting her return and that they can take her back to Homeworld. Amethyst convinces the Rubies to allow her to stay on Earth with the pretext of keeping the Crystal Gems prisoner. Using the Roaming Eye, the Rubies and the Crystal Gems travel to the Moon Base after "Doc" tells Amethyst that she will need to file a report to Yellow Diamond. At the base, they discover the main panel destroyed and the Diamond Communicator missing. After Amethyst gives "Eyeball" the task of filing the report for her back on Homeworld, the Rubies board the Roaming Eye and prepare to leave. "Doc" exits the ship to offer Amethyst a ride back to Earth and sees her in her normal form. With her disguise revealed, "Doc" orders the other Rubies to assemble and they fuse to fight the Crystal Gems. After Steven opens the airlock, Sardonyx forces the Ruby fusion to un-fuse and the Rubies are sucked out into the vacuum of space.
When the Gems and Steven leave Earth in the Roaming Eye on their way to rescue Greg from Pink Diamond's Zoo, they accidentally hit "Doc" and she sticks to the windshield briefly before rolling off.
Post-"Room for Ruby"
"Navy" presumably rescued "Eyeball" from space with the Roaming Eye, as "Eyeball" appears on Homeworld in "The Trial". It is unknown whether or not "Navy" also rescued "Doc".
"Doc" possesses standard Gem abilities.
- Pyrokinetic Touch: Like the Crystal Gem Ruby, "Doc" is shown to be able to set things on fire by touching them. This is shown in "Hit the Diamond" when she sets the baseball on fire before throwing it.
- Photokinesis: In "Back to the Moon", she is shown projecting a red light from her gem as the Gems exit the Roaming Eye. She shares this ability with Garnet, Pearl, Peridot, "Eyeball", and the Rutile Twins.
- Piloting: As shown in "Back to the Moon", she is an expert pilot who is able to fly the Roaming Eye. She shares these skills with Pearl, Peridot, and "Navy".
- When fused with "Eyeball", "Army", "Navy", and "Leggy", they form "Giant Ruby".
|1. "Super Watermelon Island":||Absent||13. "Kiki's Pizza Delivery Service":||Absent|
|2. "Gem Drill":||Absent||14. "Monster Reunion":||Absent|
|3. "Same Old World":||Absent||15. "Alone at Sea":||Absent|
|4. "Barn Mates":||Absent||16. "Greg the Babysitter":||Absent|
|5. "Hit the Diamond":||Debut||17. "Gem Hunt":||Absent|
|6. "Steven Floats":||Absent||18. "Crack the Whip":||Absent|
|7. "Drop Beat Dad":||Absent||19. "Steven vs. Amethyst":||Absent|
|8. "Mr. Greg":||Absent||20/21. "Bismuth":||Absent|
|9. "Too Short to Ride":||Absent||22. "Beta":||Absent|
|10. "The New Lars":||Absent||23. "Earthlings":||Non-speaking|
|11. "Beach City Drift":||Absent||24. "Back to the Moon":||Appears|
|12. "Restaurant Wars":||Absent||25. "Bubbled":||Non-speaking|
|1. "Kindergarten Kid":||Absent||14. "The Zoo":||Absent|
|2. "Know Your Fusion":||Absent||15. "That Will Be All":||Absent|
|3. "Buddy's Book":||Absent||16. "The New Crystal Gems":||Absent|
|4. "Mindful Education":||Absent||17. "Storm in the Room":||Absent|
|5. "Future Boy Zoltron":||Absent||18. "Rocknaldo":||Absent|
|6. "Last One Out of Beach City":||Absent||19. "Tiger Philanthropist":||Absent|
|7. "Onion Gang":||Absent||20. "Room for Ruby":||Mentioned|
|8/9. "Gem Harvest":||Absent||21. "Lion 4: Alternate Ending":||Absent|
|10. "Three Gems and a Baby":||Absent||22. "Doug Out":||Absent|
|11. "Steven's Dream":||Absent||23. "The Good Lars":||Absent|
|12. "Adventures in Light Distortion":||Non-speaking||24. "Are You My Dad?":||Absent|
|13. "Gem Heist":||Absent||25. "I Am My Mom":||Absent|
|Steven Universe: The Movie:||Imagined|
"Doc" is the leader of the group, commanding them around and initiating their fusion by calling out "Rubies assemble!" She is a strict leader, often reminding the others to focus on the mission at hand. In her strictness, she is a bit rude, as she pushed "Leggy" out of their spaceship at the beginning of "Hit the Diamond" when the unsure latter was taking too long to get out. However, she also grabbed "Leggy"'s hand at the end of the said episode to make her come with them, demonstrating some care to not leave her behind. During their fusion, she stands in the middle, being the connection point to all the other Rubies.
"Doc", like the rest of the Homeworld Gems, expresses dislike for the Crystal Gems for being their enemies, but also for being tricked and lied to. During the baseball game in "Hit the Diamond", she befriended the Crystal Gem Ruby thinking she was a Homeworld Gem but was later shown to dislike her when she and Sapphire fused and exposed their identities as Gems.
In "Back to the Moon", Amethyst shape-shifts into Jasper to fool the Rubies again. Amethyst is able to impress and amuse the Rubies, making them comfortable in her presence. They sympathize with her story of keeping the Crystal Gems prisoner, crying and clapping because of her apparent devotion. They are seen playing along with her when she pokes fun at Pearl for being talkative, kicks some dirt to demonstrate her animosity towards the Earth, or gives the Crystal Gems the silly nickname "Crystal Germs".
"Doc" uses respectful language when talking to her, and offers her the captain's seat in the Roaming Eye when they decide to head to the Moon Base. "Doc" is happily surprised and blushes when Amethyst pulls her to sit on her lap and even offers to do it again when asking Amethyst if she needs a ride back to Earth at the end of "Back to the Moon".
When Amethyst reveals her true form, "Doc" becomes angry at having been tricked again and orders her team to attack the Crystal Gems.
She mentions Yellow Diamond frequently, reminding the other Rubies that they cannot mess their mission up, as they had received direct orders from her. Surprisingly, "Doc" rather informally refers to her as just "Yellow" in "Back to the Moon", when she tells the others that "Yellow will definitely wanna know about ["Jasper" capturing the Crystal Gems]".
- The ruby is closely associated with aspects such as vitality, life, passion, and fire, all of which can be symbolically linked to the color red.
- The name "Doc" (as well as the naming conventions for the others in the Ruby squad) is a reference to Snow White and the Seven Dwarfs, in which each dwarf is named after his personality (Grumpy, Sleepy, Sneezy etc.) save for one dwarf simply named "Doc", who like the Ruby, is also the leader of his group.
- Despite being the leader of the Ruby squadron, "Doc" is seemingly younger and less knowledgeable than "Eyeball", as the latter was the only one of her squad to know where the Moon Base was.
|"Doc" has a red stone located on her chest. It has a square aspect, the front and back are symmetrical, and it has a light pink ring around it, which is usually hidden inside her body, except when she is regenerating. It is a decahedron, specifically a truncated tetragonal dipyramid.|