|This article is about The Cluster. You may be looking for Cluster Gems or the soundtrack.|
Want to stay... But... Can't stop! Going to form! Can't stop! Going to form! Help! Help! Help! Help...
|—The Cluster, "Gem Drill"|
The Cluster is a massive Cluster Gem buried inside of the Earth's core that was first mentioned in "Jail Break" and first seen in "Gem Drill". It is composed of millions of Gem shards and, in its emerged form, would be larger than the Earth. It assisted Steven in bubbling itself in "Gem Drill" and remained dormant in the Earth's mantle until it was disrupted by the ships of Yellow Diamond and Blue Diamond in "Reunited", after which it partially emerged to help the Crystal Gems. As of "Homeworld Bound", Yellow Diamond vows to restore as many shattered Gems inside of the Cluster as she can.
At some point during the Rebellion, Homeworld Gems no longer saw Earth as a viable colony, likely due to Pink Diamond being allegedly "shattered" by Rose Quartz. Instead of exploiting the planet for its resources like originally intended, Homeworld Gems planned on planting a geo-weapon inside Earth itself with the intent of destroying the planet and any remnants of the Crystal Gems. It is heavily implied later on in the series that Yellow Diamond commanded the Cluster project in order to erase Earth from Homeworld's history, not only erasing the embarrassment of a failed colony, but erasing the overwhelming grief the Diamonds felt for Pink Diamond's alleged death.
These early experiments only combine two or three shards. The Cluster will be a billion times bigger. An inseparable fusion capable of destroying worlds, starting with this one.
|—Peridot, "Gem Drill"|
The shards of fallen Gems from the ongoing war were collected by Homeworld Gems and experimented upon, forcibly fusing the shards together into Cluster Gems. Once enough experimentation was completed, Homeworld Gems fused together millions of Gem shards. This massive assortment of Gems was then planted into the Earth's mantle at the Beta Kindergarten. When this beast, known as the Cluster, takes on its physical form, it will be much bigger than the Earth itself, completely ripping the planet apart inside-out. As implied by Yellow Diamond and Peridot, Homeworld can then use the Cluster as a weapon to destroy other worlds.
As the Cluster is an aggregation of many gem shards, its personality can be likened to a hive mind. They seem to retain some consciousnesses as a collective, however, as Steven's actions in "Gem Drill" make it bubble itself. This is further shown in "Reunited", where the Cluster behaves as a single entity and fights Yellow Diamond's Ship on its own, recognizing Steven and giving him a thumbs up. It apparently has trouble with maintaining a cohesive form, and constantly worries about losing its form, as evidenced by its statement, "Want form.".
The whole point of coming here was to check on the Cluster!
|—Peridot, "Jail Break"|
Look, I know you're scared, but I'm not going to hurt you. And whatever's going on, whatever the Cluster is, I wanna help.
|—Steven, "Catch and Release"|
Open the door, Peridot! If this Cluster is putting us in danger, you need to tell us what it is so we can stop it.
|—Garnet, "When It Rains"|
This is the Cluster. A massive, artificial fusion composed of millions of Gem shards. It has laid dormant for thousands of years within this planet's crust. When this Gem activates and takes its form, the result will be catastrophic.
|—Peridot, "Back to the Barn"|
Gotta find the right file... aha! Cluster, Cluster, where are you, Cluster? Aha! There's the insertion point. Looks like the Beta Kindergarten in Facet Nine. It's the smaller of the two, not nearly as impressive as yours, Amethyst.
|—Peridot, "It Could've Been Great"|
But the Diamonds are bad! They don't care about the Earth! They wanted to hollow it out, and now they wanna blow it up with the Cluster!
|—Steven, "Message Received"|
The ground shook. This could be the start of the emergence of the Cluster. Stage 1: Slight tremors every quarter-hour. Stage 2: Full-scale earthquakes. Stage 3: the Earth is destroyed! We're running out of time. We need to drill right now!
|—Peridot, "Super Watermelon Island"|
Ugh! Am I the only one who understands the meaning of teamwork?! Okay, Steven, are you ready to drill down into the planet to depths never before reached by your species to stop the Cluster before it forms and save your world?!
|—Peridot, "Gem Drill"|
The Cluster is mentioned briefly by Blue Diamond to Greg, who also mentions that Earth does not have much time left before it is destroyed by the Cluster, not aware of its bubbling.
The Cluster is mentioned briefly by Yellow Diamond, who asks Sapphire if it has already emerged, to which the latter replies it has not.
Peridot mentions how if it wasn't for herself, Steven would have crumbled under the Cluster's destructive force.
Yellow and Blue Diamond arrive on Earth and awaken the Cluster. Its bubble is popped, and it begins to form. However, instead of going on a rampage and destroying Earth, it manages to stabilize and only form a small fragment of itself in the form of an arm, it sides with the Crystal Gems and fights Yellow Diamond's ship. After both Diamond warships are defeated, the Cluster returns to the core of the Earth and presumably bubbles itself again.
Yellow Diamond expresses the desire to undo her Gem fusion experiments, mentioning how she'd like to reconstruct the Gems that make up the Cluster.
The Cluster appears quite suddenly after noticing Steven's transformation into a monster, briefly holding him back from attacking Beach City and giving Steven's friends time to recuperate thanks to Connie's motivational speech. After briefly dispersing, it then comforts Steven along with many of his friends and family, allowing Steven to return to his normal state.
The Cluster is an immensely powerful geo-weapon designed to obliterate whole planets. The simple act of taking form would result in the destruction of the Earth, after which it would be used to devastate other planets. Unlike other fusion experiments, the Cluster has achieved a degree of control over itself. Its gemstone is immensely durable, withstanding penetration from a drill that could effortlessly pierce several strata of the Earth's crust and mantle.
Its nature as an artificial fusion of millions of Gem shards grants it many unique properties. It is the only known Gem to be able to create bubbles before taking form and to remain sentient and able to converse with itself while itself in a bubble.
- Partial Formation: In "Reunited", the Cluster demonstrated that it can form as only a minuscule fraction of what its actual size is supposed to be, in order to avoid destroying the Earth. When it did so, the portion of it that emerged from the planet's crust in the form of a massive arm was roughly the size of a Diamond's ship. This form is not sustainable, as shown when it began to be destabilized after the fight. The Cluster can voluntarily dispel it at any given time.
- Extrasensory Awareness: The Cluster's arm was able to precisely interact with its surroundings and with Steven without possessing any visible sensory organ.
- Immense Strength: When it manifested as an arm, the Cluster punched through all layers of metal and rock between its location and the Earth's surface in mere seconds, and before taking form. Later, it was able to block Yellow Diamond's Ship when it tried to ram into it before matching and eventually overpowering it, also crushing Blue Diamond's Ship in the process.
|1. "Gem Glow":||Absent||14. "Lars and the Cool Kids":||Absent|
|2. "Laser Light Cannon":||Absent||15. "Onion Trade":||Absent|
|3. "Cheeseburger Backpack":||Absent||16. "Steven the Sword Fighter":||Absent|
|4. "Together Breakfast":||Absent||17. "Lion 2: The Movie":||Absent|
|5. "Frybo":||Absent||18. "Beach Party":||Absent|
|6. "Cat Fingers":||Absent||19. "Rose's Room":||Absent|
|7. "Bubble Buddies":||Absent||20. "Coach Steven":||Absent|
|8. "Serious Steven":||Absent||21. "Joking Victim":||Absent|
|9. "Tiger Millionaire":||Absent||22. "Steven and the Stevens":||Absent|
|10. "Steven's Lion":||Absent||23. "Monster Buddies":||Absent|
|11. "Arcade Mania":||Absent||24. "An Indirect Kiss":||Absent|
|12. "Giant Woman":||Absent||25. "Mirror Gem":||Absent|
|13. "So Many Birthdays":||Absent||26. "Ocean Gem":||Absent|
|27. "House Guest":||Absent||40. "On the Run":||Absent|
|28. "Space Race":||Absent||41. "Horror Club":||Absent|
|29. "Secret Team":||Absent||42. "Winter Forecast":||Absent|
|30. "Island Adventure":||Absent||43. "Maximum Capacity":||Absent|
|31. "Keep Beach City Weird":||Absent||44. "Marble Madness":||Absent|
|32. "Fusion Cuisine":||Absent||45. "Rose's Scabbard":||Absent|
|33. "Garnet's Universe":||Absent||46. "Open Book":||Absent|
|34. "Watermelon Steven":||Absent||47. "Shirt Club":||Absent|
|35. "Lion 3: Straight to Video":||Absent||48. "Story for Steven":||Absent|
|36. "Warp Tour":||Absent||49. "The Message":||Absent|
|37. "Alone Together":||Absent||50. "Political Power":||Absent|
|38. "The Test":||Absent||51. "The Return":||Absent|
|39. "Future Vision":||Absent||52. "Jail Break":||Mentioned|
|1. "Full Disclosure":||Absent||14. "Historical Friction":||Absent|
|2. "Joy Ride":||Absent||15. "Friend Ship":||Absent|
|3. "Say Uncle":||Absent||16. "Nightmare Hospital":||Absent|
|4. "Love Letters":||Absent||17. "Sadie's Song":||Absent|
|5. "Reformed":||Absent||18. "Catch and Release":||Mentioned|
|6. "Sworn to the Sword":||Absent||19. "When It Rains":||Mentioned|
|7. "Rising Tides, Crashing Skies":||Absent||20. "Back to the Barn":||Mentioned|
|8. "Keeping It Together":||Absent||21. "Too Far":||Absent|
|9. "We Need to Talk":||Absent||22. "The Answer":||Absent|
|10. "Chille Tid":||Absent||23. "Steven's Birthday":||Absent|
|11. "Cry for Help":||Absent||24. "It Could've Been Great":||Mentioned|
|12. "Keystone Motel":||Absent||25. "Message Received":||Mentioned|
|13. "Onion Friend":||Absent||26. "Log Date 7 15 2":||Absent|
|1. "Super Watermelon Island":||Mentioned||13. "Kiki's Pizza Delivery Service":||Absent|
|2. "Gem Drill":||Debut||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":||Absent||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":||Absent|
|11. "Beach City Drift":||Absent||24. "Back to the Moon":||Absent|
|12. "Restaurant Wars":||Absent||25. "Bubbled":||Absent|
|1. "Kindergarten Kid":||Absent||14. "The Zoo":||Absent|
|2. "Know Your Fusion":||Absent||15. "That Will Be All":||Mentioned|
|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":||Absent|
|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":||Mentioned||23. "The Good Lars":||Absent|
|12. "Adventures in Light Distortion":||Absent||24. "Are You My Dad?":||Absent|
|13. "Gem Heist":||Absent||25. "I Am My Mom":||Absent|
|1. "Stuck Together":||Absent||15. "Pool Hopping":||Absent|
|2. "The Trial":||Absent||16. "Letters to Lars":||Absent|
|3. "Off Colors":||Absent||17. "Can't Go Back":||Absent|
|4. "Lars' Head":||Absent||18. "A Single Pale Rose":||Absent|
|5. "Dewey Wins":||Absent||19. "Now We're Only Falling Apart":||Absent|
|6. "Gemcation":||Absent||20. "What's Your Problem?":||Absent|
|7. "Raising the Barn":||Mentioned||21. "The Question":||Absent|
|8. "Back to the Kindergarten":||Absent||22. "Made of Honor":||Absent|
|9. "Sadie Killer":||Absent||23/24. "Reunited":||Appears|
|10. "Kevin Party":||Absent||25. "Legs From Here to Homeworld":||Mentioned|
|11. "Lars of the Stars":||Absent||26. "Familiar":||Absent|
|12. "Jungle Moon":||Absent||27. "Together Alone":||Absent|
|13. "Your Mother and Mine":||Absent||28. "Escapism":||Absent|
|14. "The Big Show":||Absent||29-32. "Change Your Mind":||Absent|
|1. "Little Homeschool":||Absent||11. "In Dreams":||Mentioned|
|2. "Guidance":||Absent||12. "Bismuth Casual":||Absent|
|3. "Rose Buds":||Absent||13. "Together Forever":||Absent|
|4. "Volleyball":||Absent||14. "Growing Pains":||Flashback|
|5. "Bluebird":||Absent||15. "Mr. Universe":||Absent|
|6. "A Very Special Episode":||Absent||16. "Fragments":||Absent|
|7. "Snow Day":||Absent||17. "Homeworld Bound":||Mentioned|
|8. "Why So Blue?":||Absent||18. "Everything's Fine":||Absent|
|9. "Little Graduation":||Absent||19. "I Am My Monster":||Appears|
|10. "Prickly Pair":||Absent||20. "The Future":||Absent|
- The plan to hollow out the Earth was foreshadowed by Ronaldo's conspiracy theories in "Keep Beach City Weird".
- Peridot refers to the Cluster as a "Gem geo-weapon". This is a play on the term "Bioweapon", Bio- referring to organic life while Geo- referring to rocks and minerals. This is appropriate, seeing as how Gems are a race of sentient gemstones and are thus inorganic.
- In "It Could've Been Great", a map on the Moon Base reveals that the Cluster is currently located somewhere around Death Valley in Southern California/Southern Nevada.
- In "Back to the Barn", Peridot was convinced that the Cluster lay exactly at the center of the Earth. It is only in "It Could've Been Great" that the correct location of the Cluster was discovered. This could be due to Homeworld being unable to implant it at originally planned due to the rebellion and the records failing to reflect that, or simply a retcon.
- Unlike Gem mutants, when the Cluster attempts to reform, its appendages are translucent.
- Also, unlike Gem mutants, it possesses a rudimentary intelligence — likely because of a hive mind formed from the shattered intellect of the millions of shards that compose it.
- As evidenced in "Steven's Dream" and "That Will Be All", the Diamonds (Blue and Yellow specifically) were unaware of the Cluster's bubbling.
- The Cluster's gemstone bears a strong resemblance to an Angel Aura Geode, while its physical form shares strong similarities to the muscular system of a human arm.
- Whenever the hand of the Cluster loses control of its physical form, it makes the same sound that Amethyst did when she "glitched" for a few seconds periodically during the time she was cracked.
- The Cluster is the only character to have eight voice actors.
- The Cluster bears a great resemblance to Lavos, the main antagonist of the Chrono Trigger video game. They are both extraterrestrial creatures that will initiate an apocalyptic event if they are released/awakened unless a group of heroes stops them.