Unknown Gems

Unknown Gems are Gems who have been visually shown through holograms, drawings, named, or other methods, but have not been identified by their name or Gem type.

"Historical Friction"
In Steven and Jamie's play, "Beach City or Bust", Obsidian fights with a Corrupted Gem resembling both the Centipeetle Mother and the Big Bird.

"When It Rains"
There are holograms of many unknown Cluster Gems in the Prime Kindergarten Control Room in "When It Rains".

"The Answer"
There are many unknown Gems (represented in silhouettes during Garnet's flashback) in "The Answer". These Gems make up Blue Diamond's court.

"Message Received"
In "Message Received", Yellow Diamond states that Peridot has a manager.

"Same Old World"
There are a few unknown Gems featured in Lapis' flashback.

"Monster Reunion"
There are a few unknown Gems featured in Nephrite's flashback.

Nephrite, upon being briefly uncorrupted in "Legs From Here to Homeworld", mentions her Hessonite commander.

"Bismuth"
These are the "other Crystal Gems" who were mentioned by Bismuth, except for Nephrite, who is most likely a Homeworld Gem. They appear to be her close friends. Their statuses and physical appearances are unknown.
 * "Crazy Lace" - A former Crystal Gem mentioned by Bismuth. She is presumably a Crazy Lace Agate.
 * "Snowflake" - A former Crystal Gem mentioned by Bismuth in. She may be a Snowflake Obsidian, a type of volcanic glass.
 * Other Amethysts - Former Crystal Gems mentioned by Bismuth.
 * Nephrite - A Homeworld ship pilot, mentioned by Bismuth to Pearl.

"Beta"
Many Corrupted Gems are seen trapped in cages in the Beta Kindergarten. Their bodies are hidden by shadows and only their glowing yellow eyes can be seen.

Additionally, Peridot mentions a Carnelian whose hole is misshaped in the Beta Kindergarten, later assumed to be Carnelian, a member of "the Famethyst" in "That Will Be All". Amethyst refers to one Gem with a thin exit hole as "skinny", later assumed to be a "Skinny" Jasper, a member of "the Famethyst" who debuted in the same episode as Carnelian.

"Earthlings"
Another Corrupted Gem can be seen in a cage. Only her two eyes and large six-clawed hand can be seen.

"Adventures in Light Distortion"
When Steven is adjusting the Roaming Eye's form calibration system for the Crystal Gems, a small type of Gem, possibly a Pebble or gems of the Earth and Heaven Beetle type, can briefly be seen on the panel, which subsequently alters the Crystal Gems' forms to be small. Also, a large type of Gem, presumably Quartz, Topaz, or Bismuth can be seen.

"That Will Be All"
A countless number of Rose Quartz gems appear bubbled in a room of Pink Diamond's Zoo.

"The Trial"
The defending Zircon states that Pink Diamond's entourage did not contain any Rose Quartzes and was instead composed of several Agates and Sapphires.

"Off Colors"
Various pieces of old statues can be seen at the beginning of the episode. One appears to be a fusion of two unknown Gems, while the head of a large statue has a gemstone with the same cut as a Rose Quartz's on its forehead.

Rhodonite's components are an unknown Ruby and Pearl, while Fluorite's components are six unknown Gems.

The Rutile Twins mention in that the moment they emerged, the other Rutiles who saw them ran away in fear because of how they looked.

Morganite, an unknown Gem, is mentioned by Rhodonite. She was in charge of the two halves of Rhodonite (a Pearl and a Ruby) before she replaced them after she found out that they had fused.

"Gemcation"
During Garnet's brief flashback of the Rebellion, two unknown Gem silhouettes appear fighting Pink Diamond alongside Garnet, Pearl and Bismuth.


 * On the left of the image there is a Gem with short hair around the same height of Pearl. She appears to have a thin build. Her hair is similar to the Rutile Twins' or the prosecuting Zircon's.
 * On the right of the image there is a short Gem. She resembles one of the unknown Gems in "The Answer".

"Lars of the Stars"
A group of sixty-seven elite Citrines is mentioned by Emerald to have guarded her fastest ship, the Sun Incinerator, on the docking bay of the planet Klavius 7. Lars and the Off Colors are able to successfully sneak past all of the guards in order to steal the ship. Emerald also mentions that one of the crimes Lars and the Off Colors are accused of is impersonating imperial officers in a cosmic jubilee. While pursuing the Off Colors in her Destiny Destroyer, Emerald commands her crew, who remain offscreen, to fire on the Sun Incinerator's nova thrusters.

"Jungle Moon"
In Stevonnie's dream, the name shown on Dr. Maheswaran (who represents Yellow Diamond in the dream)'s phone is Nephrite-XJ Cut-763. She seems to have been reluctant to begin colonizing the planet due to the presence of organic life, causing Yellow Diamond to demand her to do her job, threatening to shatter her and her crew herself otherwise. According to the silhouette on the phone, she has spiky hair.

Yellow Diamond also attempts to contact the leader of the fleet, however, Pink Diamond interrupts her, so the leader's name and appearance are never shown.

"Your Mother and Mine"
During the flashback, many Quartzes belonging to Pink Diamond appeared, emerging from their incubation in the ground alongside Rose Quartz. The silhouettes of other Quartzes, whose purple coloring suggesting they are Amethysts, are also shown working in the kindergarten. Unknown Crystal Gems also appeared in the flashback, standing alongside Rose and fighting unknown Homeworld Gems at the Ancient Sky Arena.

Near the end of the episode, Rhodonite said there will be Agates on one of Yellow Diamond's Asteroid Mines that they were heading towards.

"A Single Pale Rose"
While Steven is in Pearl's gemstone, he presumably discovered her memories of the abandoned Gem Battlefield the second Pearl sent him to. There when he fell, he saw gemstones of inactive Gems in the sand. Later in the scene when Steven comes back from Pearl's gemstone, there are many Gems that witnessed Pink Diamond's shattering. In a following scene, there is a flail-wielding white Gem that Garnet poofs, and a Gem with a sword that Pearl fights.

"Now We're Only Falling Apart"
Three Amethysts appear in a flashback alongside Pearl, Rose Quartz, and two Topazes. They have large hair covering their eyes and a Blue Diamond insignia on their uniforms.

"The Question"
Ruby mentioned being surrounded by other Rubies before meeting Sapphire.

"Made of Honor"
After Bismuth is unbubbled in the Burning Room, she reveals the names of several bubbled (and presumably corrupted) former Crystal Gems.
 * "Tiger's Eye" - A corrupted Crystal Gem mentioned by Bismuth, formerly bubbled in the Burning Room, and presumably uncorrupted as of "Change Your Mind ".
 * "Larimar" - A corrupted Crystal Gem mentioned by Bismuth (nicknamed "Little Larimar"), formerly bubbled in the Burning Room, and presumably uncorrupted. Her nickname implies that she is of short stature.
 * "Beryl" - A corrupted Crystal Gem mentioned by Bismuth, formerly bubbled in the Burning Room, and presumably uncorrupted.
 * "Serpentine" - A corrupted Crystal Gem mentioned by Bismuth, formerly bubbled in the Burning Room, and presumably uncorrupted.

"Legs From Here to Homeworld"
Upon the arrival of Pink Diamond's ship, many Gems are seen cheering for the Diamonds. Among the Gems seen in the close-up of the crowd are a group of green Gems, presumably Peridots, a group of short pink Gems, a group of pale blue Gems, and a group of flying Aquamarines.

"Familiar"
Yellow Diamond is mentioned to be checking up on Citrine production reports.

Blue Diamond mentions that Pink Diamond used to call a batch of Pyrite "Fool's Gold".

There are several polygonal yellow Sentient Walls (presumably Gems or Gem-powered objects) that seem to make up the wall in the hallway leading to Yellow Diamond's Extraction Chamber. They all have a rhombus-shaped yellow gemstone on their forehead.

There is also a Sentient Statue making up part of the entryway to Blue Diamond's pool chamber. The statue is capable of blinking and has a round gemstone on their forehead, so they seem to be a Gem or a Gem-powered object like Lapis's mirror.

"Together Alone"
Various types of Garnets — Demantoids, Hessonites, and Pyropes — are mentioned by Blue Diamond when she taunts Garnet. In addition, some unknown gems can be seen attending the Era 3 Ball. In addition to various Jades, Aquamarines, Amethysts, Jaspers, Rubies, and Sapphires, these blue-green gems can be seen.

In addition:
 * There is a green statue-like Gem (or Gem-powered object) with a disco ball contained within it, as wells large green hands. Whether or not if this disco ball is this Gem's gemstone or not is currently unknown.

"Change Your Mind"
In Steven's dream flashback, Blue Diamond mentions a Kyanite colony, though whether she was referring to a planet called Kyanite or a planet that produces Kyanite Gems is unclear. The silhouettes of unknown Gems can be seen surrounding and staring at Steven during his dream. Inside Yellow Diamond's bubble room, there are a number of unknown bubbled cluster gems. There are also yellow Sentient Bridges (presumably Gems or Gem-powered objects) seen leading to Yellow Diamond's bubble room, and on the bridge Yellow and Blue Diamond land on after the former shoves the latter through the bubble room wall.

Steven Universe: The Movie
An unknown reddish-pink Gem is shown in the teaser trailer for Steven Universe: The Movie, presumably serving as the film's antagonist. She has her gemstone, which appears to be heart-shaped, on her chest.

Heap of Trouble
There are some unknown Gems in Heap of Trouble.

Attack the Light
There is an unknown Gem from Steven Universe: Attack the Light.

Save the Light
During a flashback to Hessonite's past, several unknown Gems are seen during the war.

Gems mentioned to be Citrines by Garnet can be heard guarding a door on Hessonite's warship, but they're not seen. The same Citrines believe the sounds they're hearing are the result of a Nephrite drill.

Steven Universe Comics
There are some unknown Gems from the Steven Universe comics.

Trivia

 * The unknown Quartz warrior in "Sworn to the Sword" is voiced by Michaela Dietz, implying she may be an Amethyst.
 * The mineral classification of the now uncorrupted Crystal Gems are as follows (as mentioned by Bismuth):
 * "Crazy Lace" is a variety of agate.
 * "Tiger’s Eye" is a variety of quartz.
 * "Beryl" is a rock type that includes the gems aquamarine, emerald, and morganite.
 * "Serpentine" refers to different gems that come from the rock Serpentinite.
 * "Larimar" refers to a variety of pectolite.
 * "Snowflake" is a type of obsidian.
 * Pink Diamond calling the Pyrites "Fool's Gold" is a tie to the nickname given to that rock in real life.
 * During the Reddit Q and A, Rebecca Sugar explains the personality of a Lepidolite if it were ever to appear in the series.