Ruby

"Ruby" is a Gem that first appears in "Jail Break." Currently, she is fused with Sapphire, as Garnet.

Appearance
Ruby has light red skin, dark maroon hair, and is slightly taller than Steven. She wears a violet-red and dark red tank top leaving her arms free, a light red headband around thick, outgrown hair cropped at the neck, mid-thigh length maroon shorts, and pointed violet-red boots. Her gemstone is located on the palm of her left hand, and has a square facet.

Personality
She takes on Garnet's strength and courage, while Sapphire embodies Garnet's cool nature and kindness. She seems to put the well-being of Sapphire over all else, as she immediately made sure Sapphire was safe and responded "Who cares?!" when Sapphire asked her if she herself was okay. She also seems to not be very conversive, a trait which carries onto Garnet, as Ruby mumbles and speaks somewhat awkwardly. She also loves Sapphire very much.

Abilities
Like all Gems, Ruby can shape shift, summon a weapon, and retreat to her gemstone to regenerate. Ruby can fuse with Sapphire to form Garnet.

Unlike her fusion with Sapphire, Garnet, Ruby doesn't possess future vision. Joe Merely confirmed that when she complained about not being able to "see" (use future vision), it was because she was so used to having that second sight while being fused with Sapphire. She is also involved in the fusions Sugilite and Alexandrite, although it is not known if she and Sapphire have to be fused first for those two to come out the same.

Unique Abilities

 * Super Strength: Ruby may have some degree of super strength as she was able to shake her cell by slamming her fist against the wall, causing Steven to lose his footing.

Sapphire
Ruby cares deeply for Sapphire, shown when she immediately panics when she realizes that the two have been separated and becomes reckless trying to find her, running around without checking if Peridot and Jasper are around and loudly shouting for Sapphire whenever she stopped singing. When she finds Sapphire, the two embrace and Sapphire kisses away Ruby's tears, showing their romantic relationship. Ruby cares strongly for Sapphire's well-being as she expressed deep concern for possible injury. It is also possible that they are related.

Steven Universe
At first Ruby seemed cold and distant towards Steven due to wanting to find Sapphire as quickly as possible. Despite this, Ruby cares deeply for Steven, as Garnet says that both her and Sapphire had already loved Steven when he asked if he made a good first impression. She also tried to stop Steven when she thought he was going to get hurt by the energy field in front of her cell.

Crystal Gems
Pearl and Amethyst have been aware of Garnet's true identities for several millennia. Their reception of those two while separated remains unknown.

Trivia

 * Ruby's gemstone can only be seen twice in her debut episode, "Jail Break."
 * Although she was not formally introduced until "Jail Break," her silhouette, along with Sapphire's, can be seen when Alexandrite breaks part in "Fusion Cuisine."
 * Ruby and Sapphire are lovers, as shown by Ruby's desperate desire to find Sapphire, and the kiss that is part of their fusion dance. It also explains why they chose to stay as their fusion, Garnet.
 * When asked if Ruby was blind, Joe Johnston merely stated that she was "used to being fused with Sapphire, and so, used to having two types of vision," making the theory of Ruby's blindness very unlikely.
 * She was probably trying to use the future vision that she is used to having when fused with Sapphire
 * Ruby is the birthstone of the creator of Steven Universe, Rebecca Sugar.
 * Ruby, along with Sapphire, both lack stars on their outfit.
 * It's possible that Ruby and Sapphire both had rooms in the Crystal Temple, due to the fact that they both have their corresponding gemstones on the door.
 * Ruby's gemstone location is not symmetrical, along with Sapphire's.
 * When fused as Garnet, however, their combined gemstones become symmetrical.
 * Ruby is the second shortest Gem, the first being Steven.
 * Although, she is the shortest full-Gem, while Steven is half-human.

Gemology
Learn more about the ruby gemstone here.
 * Ruby is a gemstone of emotion, associated with passion, strength and anger. This shows in Ruby's emotional temperaments and overall emotional/angry attitude.
 * Ruby is the birthstone of July.