Minor Characters/Gems

Minor Gem Characters are Gems who have debuted and been identified, but, as of yet, hold no significant nor recurring roles.

Rubies
All Rubies shown thus far, including the Crystal Gems' Ruby, are voiced by Charlyne Yi.

Ruby (right shoulder gem)
Ruby is a Gem who appears in "The Answer".

She appears to be identical to the Crystal Gem Ruby and the other Ruby in their Gem trio in appearance, clothing, and voice. She and the other Ruby seem to be obsessed with fighting. Her gemstone is also identical and is placed on her right shoulder.

Ruby (right back-hand gem)
Ruby is a Gem who appears in "The Answer".

She appears to be identical to the Crystal Gem Ruby and the other Ruby in their Gem trio in appearance, clothing, and voice. She and the other Ruby seem to be obsessed with fighting. Her gemstone is also identical and is placed on the back of her right hand.

Quartz
All Amethysts shown thus far, including the Crystal Gems' Amethyst, are voiced by Michaela Dietz.

Jasper, "Skinny" Jasper, and Carnelian are voiced by Kimberly Brooks.

Four Amethysts appear in "Gem Heist"; 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. This may be an animation error.

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

Carnelian
Carnelian is a defective quartz soldier from the Beta Kindergarten who briefly appeared in "That Will Be All". She is, like the Crystal Gems' Amethyst, smaller than she should be.

Ruby (triple fusion)
Ruby (triple fusion) is the fusion of all three Rubies in "The Answer", one of which is the Crystal Gem, Ruby.

As their individual forms and gemstones are the same, their fusion remains identical except much larger in size. In this form, they are much more powerful. However, the actual extent of their strength in this form remains unclear because they fought against Rose Quartz, an extremely skilled and powerful warrior. The Crystal Gem Ruby describes the fusion as just "me, but bigger," implying the state of being is not that different for her unfused.

Ruby (quintuple fusion)
Ruby (quintuple fusion), also known as "Giant Ruby" in the credits of "Back to the Moon", is the fusion of all five Homeworld Rubies who debuted in Hit the Diamond (except "Eyeball", who debuted briefly in Barn Mates).

As their individual forms and gemstones are the same (minus the left eye gemstone fitting over the left pupil), their fusion remains identical except a larger size, and a slight outfit variation (including Doc's yellow visor). The Ruby fusion has a gemstone on her chest, her navel, her left arm, her left leg, and in her left eye.

When first formed in her debut, "Hit the Diamond" (asking threateningly for the location of Jasper), the Ruby fusion had a firm and interrogative tone (somewhat matching "Doc's" personality). However, once given the answer, her voice became higher and happier (a complete mood swing), similar to that of "Leggy."

Formed again in Back to the Moon, "Giant Ruby" fused when the Rubies realized they had been tricked for the second time. Originally confronting Garnet, Amethyst, and Pearl, the fusion turned her anger on Steven as he was about to open the door to the Moon Base. At first, the Ruby fusion held onto the doorframe to keep from being swept out, but Sardonyx formed and hit the Ruby fusion with her hammer. Sardonyx's attack was enough to unfuse the Rubies and send them flying into space.

Trivia

 * So far, it is true that Gems of the same gemstone also share the same voice, albeit with some differences in tone. Their appearances are also nearly identical, excluding gemstone placement and minor outfit details.
 * In "Hit the Diamond", it is revealed that Rubies are typically unintelligent and easily fooled. Being as Rubies are the Gem equivalent to foot soldiers and common enough to be effectively expendable, high intelligence isn't a necessity.
 * According to Ian Jones-Quartey, if the Pearls fused, they would form a bigger Pearl with combined colors.
 * This idea is shown when the Rubies fused.