Quartzes

Quartzes are a broad collection of Gems cuts that serve as the primary soldiers of Homeworld's Caste System. Some Quartzes are higher ranking than others, being described as "elite" or holding commander positions while the majority maintains a common soldier ranking.

Role
Quartzes are a soldier caste. Some Quartzes are used as bodyguards and escorts as shown in Jasper's case. They appear to be less numerous than Rubies. According to Ian Jones-Quartey, some have defensive powers as well (like Rose's) since "they can't all be tanks." Jasper stated that Quartzes are made to fight and Jaspers specifically always get what they want. Some also act as guards at Homeworld outposts such as Pink Diamond's zoo. They were commonly made on Earth. Quartzes are the most diverse known Gem type with Gems including Amethysts, Carnelians, Jaspers and Rose Quartzes.

Other Quartz types include Agates, who rank higher and seem to be administrative in nature and Citrines, who seem to be elite guards (including Emerald and Hessonite's guards).

Physical Characteristics
Quarztes are much larger than most other types of gems, made to fit the role of an elite warrior, Quartzes have incredible height, broad shoulders, and an intimidating muscular build. While their exact height can vary depending on how well they formed when they were incubating in the ground, most quartzes appear to be the same height as each other, with variations of this standard height being very rare. Quartzes (excluding Agates) have some of the longest and thickest hair of any gem. Their hair colour is often a very pale tone of the colour of their gem, although some have dark brown hair.

All Homeworld Quartzes wear the standard Homeworld uniform, while quartzes with a more managerial position, such as Agates, wear an additional shawl and boots. Decorated Quartzes, such as Jasper, can also wear a cape over their uniform, though this isn't actually a part of their physical form.

When Corrupted, Jasper gems take the form of a giant eyeless wolf-like beast. They have a furry mane which extends down their back and covers their tail, and they can have a number of horns on their head. Based on the appearance of Blue Lace Agate and Lace Amethyst when uncorrupted, other varieties of Quartz likely take on a similar appearance, although this has not been shown in full.

Main Quartzes
Quartzes with their own articles include:
 * Amethyst Facet-5 Cut-8XM - An Amethyst created in the Prime Kindergarten. She emerged long after The Rebellion and joined the remaining Crystal Gems.
 * Jasper - A Jasper from the Beta Kindergarten. She fought against the Crystal Gems during the Rebellion, holding a personal resentment towards Rose Quartz for shattering Pink Diamond.
 * Holly Blue Agate - A Holly Blue Agate who is in charge of a group of Quartz soldiers and manages Pink Diamond's Zoo.
 * "Skinny" Jasper - A defective Jasper debuting in "That Will Be All", and a member of the the "Famethyst".
 * Carnelian - A defective and short Carnelian debuting in "That Will Be All", and a member of the "Famethyst".
 * Biggs Jasper - A member of the Crystal Gems who was corrupted at the end of the war but later healed during the events of "Change Your Mind".
 * "Snow Monster" - A type of Jasper who was corrupted during the end of the war but was also healed in "Change Your Mind".
 * Cherry Quartz - An uncorrupted Cherry Quartz from the war who Steven tours around Little Homeworld in Steven Universe Future.

Agates
Agates hold a position of authority slightly higher than other Quartzes. They appear to serve as a form of manager for groups of other types of Quartzes, keeping them in line and ensuring that they perform their duties. So far, Holly Blue Agate is the only major Agate to be shown so far. She is in charge of a group of Quartz soldiers and manages Pink Diamond's Zoo. Other types of Agates have been mentioned such as:
 * Crazy Lace Agate - An Agate who is a member of the Crystal Gems. It is worth noting that she is possibly an Agate fusion, or a fusion of two other types of Quartz.
 * Blue Lace Agate - An uncorrupted Agate that can be seen during the end of "Change Your Mind" and in Little Homeworld during Steven Universe: The Movie.
 * Pink Diamond's Agates - Agates who used to belong to Pink Diamond, they were her bodyguards during the Rebellion, first mentioned by Blue Zircon in "The Trial".
 * Yellow Diamond's Agates - Agates who reside in one of Yellow Diamond's Asteroid Mines and first mentioned by Rhodonite in "Your Mother and Mine".
 * Unknown Holly Blue Agate - A Holly Blue Agate seen watching Steven's message in an unknown gem city. Her gem is located on her lower back.

Amethysts
Amethysts are a purple type of Quartz, most notably produced on Earth's Prime Kindergarten for Pink Diamond. Besides Amethyst 8XM, the Amethysts from Earth were stationed at Pink Diamond's Zoo thousands of years later, now serving Blue Diamond and are commanded by Holly Blue Agate due to the "shattering" of Pink. Like Amethyst 8XM, these Amethysts share a laid back and comedic personality.

History
Four Amethysts appear in "Gem Heist" at Pink Diamond's Zoo; two of them are in charge of guarding the door in the Zoo's cargo bay. The two Amethysts tease the Crystal Gems when they land on the Zoo, resulting in a scolding from Holly Blue Agate. Later in "Gem Heist," another pair of Amethysts send Steven into the Zoo's tunnel, one with a square-faceted gemstone.

In "The Zoo," several Amethysts are seen entering the boundaries of Pink Diamond's Zoo to console the heartbroken Zoomans. One Amethyst later angrily informs Greg and Steven of the trouble they are in.

In "That Will Be All", this turns out to be a prank by Amethyst and the many other Homeworld Quartz guards she has met (whom she refers to collectively as "the Famethyst"), three of which having been formed right above her. These Amethysts inform her of her serial number being Facet-5 Cut-8XM. Among the Amethysts and Jaspers are two defective Gems: "Skinny", a tall and skinny Jasper, and Carnelian, shorter than most Quartzes.

In "Now We're Only Falling Apart", numerous Amethysts are shown emerging out of the Prime Kindergarten in a flashback from Pearl.

In "Together Alone", several Amethysts and Jaspers are shown in the crowd of Quartz Gems dancing alongside the Crystal Gems' Amethyst during the Era 3 Ball.

"Now We're Only Falling Apart"
Many Amethysts appear in Pearl's flashback, all of which emerging from the Prime Kindergarten.

"Together Alone"
Several Amethysts attend the Era 3 ball, seen dancing along with several Jaspers.

"Change Your Mind"
Lace Amethyst, an uncorrupted Quartz Gem, can be seen during the end of "Change Your Mind", as well as in Little Homeworld during Steven Universe: The Movie and Steven Universe Future.

The Phantom Fable
They appear in Delta Kindergarten. They are all enemies.

Jaspers
Jaspers are a broad variety of Quartz soldiers that vary in color, such as Biggs Jasper and the Snow Monster. The famous Jasper describes her cut as never giving up and always getting what they want.

"That Will Be All"
Several Jaspers from the Beta Kindergarten debuted in "That Will Be All". Like the Amethysts, they originally belonged to Pink Diamond but now served Blue. Despite their Gem type, they are all considered members of the "Famethyst".

"Together Alone"
Two identical Jaspers attend the Era 3 ball, seen dancing along with several Amethysts. They likely appear as duplicates of one another to fill crowd space.

"Change Your Mind"
This greenish Jasper is seen among the Gems being healed, her coloration and spotted patterns indicate her to be another Ocean Jasper, but she visibly possesses different patterns, indicating that she is a different instance.

The Phantom Fable
She appears in Delta Kindergarten.

Carnelians
Carnelians are a red type of Quartz. Some Carnelians are
 * Carnelian, a defective and short Carnelian debuting in "That Will Be All", and a member of The "Famethyst".

Rose Quartzes
Rose Quartzes are a pink type of Quartz which appear to be designed in the visage of Pink Diamond.

"That Will Be All"
Steven and his father Greg saw the bubbled Rose Quartz Gems in Pink Diamond's Zoo.

"The Trial"
They were mentioned by defending Zircon that there's no Rose Quartz soldiers in Pink's entourage.

"Rose Bud"
Several unbubbled Rose Quartzes appear. Amoung these is one who looks exactly like Pink Diamond's Rose Quartz disguise.

Three main ones, the focus of the episode, spend time with Steven and try to have a slumber party at his house. They pretend to be happy to please him while he pretends to enjoy their presence, but when he reveals his discomfort with being reminded of his mother, they each reveal that they were putting on a front as well. Steven then changes his mind to consider them siblings, as they were all created by his mother and have to live under her shadow. Steven says to visit soon as they return to the Human Zoo ship.

Cherry Quartzes
Cherry Quartzes are a type of large and pink Gem. The role of them is unknown, but they can be presumed to have had a similar role to the other Quartz Gems. Some Cherry Quartzes are
 * Cherry Quartz, an uncorrupted Gem who Steven tours around Little Homeworld in Steven Universe Future.

Angel Aura Quartzes
Angel Aura Quartzes are multicolored Quartzes. Their role is unknown, but they can be presumed to have a similar role to other Quartzes.
 * Angel Aura Quartz, a formerly corrupted quartz that first appeared in "Change your Mind".

Citrines
Citrines are a yellow type of Quartz who seem to be an elite caste of guards serving high-ranking Gems.

Tiger's Eyes
Tiger's Eyes are a type of Quartz which is yet to be seen but has been mentioned by name.

Quartz in "Sworn to the Sword"
Unknown Quartz warrior in Pearl's hologram flashback of the Rebellion; voiced by Michaela Dietz. She has a similar appearance to Jasper.

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

Quartzes in "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.

Quartzes in "Change Your Mind"
At Rose's Fountain, a Gem with thick brown hair can be seen from behind talking to the healed Snow Monster, but no other details of her are shown; she appears to be a Quartz.

Steven Universe: The Movie
Four unidentified quartzes can be seen from behind watching Steven's message.

Unnamed Blue Quartzes
These gems appear in The Phantom Fable. Their weapons are large tipped spears.

Quartz Fusions

 * Zebra Jasper - The half-corrupted fusion of two Jaspers, Jasper and the corrupted Snow Monster Jasper. Her formation resulted in the former becoming corrupted herself. Whether her mutant-like appearance is because of her two component Jaspers being of different varieties, or limb duplication caused by corruption, has not been stated.
 * Crazy Lace Agate - A citizen of Little Homeworld as well as a Crystal Gem. She appears to be the fusion of two Quartzes.

Beta Kindergarten Quartz Monsters
The Beta Kindergarten Quartz Monsters are Corrupted Gems that appeared in the episode "Earthlings". Their designs' similarities to other Corrupted Gems (including the corrupted form of Jasper and Biggs Jasper) imply they are Quartz.

Jasper originally incarcerated them as she was forming her Corrupted Gem army to take on the Crystal Gems. Jasper accidentally frees the Corrupted Gems when she crashed into a cliff face and knocked several free from their cells.

Their current status is unknown after running off, but they are assumed to be somewhere near the Beta Kindergarten.

As confirmed by Rebecca Sugar, they are types of Jasper.

Trivia

 * All Amethysts are voiced by Michaela Dietz; all Jaspers, Carnelian, Cherry Quartz, and Angel Aura Quartz, are voiced by Kimberly Brooks.
 * So far, it is true that Gems of the same gemstone (with the exception of the Diamonds) also share the same voice, albeit with some differences in tone. Their appearances are also nearly identical, excluding gemstone placement and details such as hair length and style, skin tone and patterning in the case of Jaspers.
 * All Jaspers, Carnelian, Cherry Quartz, and Angel Aura Quartz are voiced by Kimberly Brooks, despite being different types of quartz – suggesting different Gems within one larger Gem type may share the same voice actor.