Blue Diamond

"I'm surprised that a human being is capable of understanding how I feel."

Blue Diamond is a Homeworld Gem and a member of the Great Diamond Authority that rules over the Gem race. She first appears in a flashback in "The Answer" and debuts in person in "Steven's Dream".

Personality
Blue Diamond's debut portrays her as a very mellow Diamond who treats high-ranking members of her court with respect. According to Holly Blue Agate, Blue Diamond has a reputation for mercy and forgiveness. "Saving" Greg from the threat of the Cluster after taking a liking to him, unaware that the Cluster is no longer active, demonstrates this. However, as with Yellow Diamond, her true nature may be at odds with her reputation, as she sentences Ruby to shattering for accidentally fusing with Sapphire while trying to do her job and saving her by accident. However, it is unknown if her personality has changed over the millennia after Pink Diamond's death.

Blue Diamond's temperament appears to have changed significantly in the 5,000 years following the death of Pink Diamond. She is currently in a state of great depression, still mourning over the shattering of her fellow diamond. She is unable to let go of the past, becoming fixated on preserving Pink Diamond's legacy. Her efforts to maintain the late diamond's zoo, save Earth specimens from the Cluster's emergence, and her refusal to shatter the rose quartzes that once served under Pink Diamond shows this behavior. She continues to regard the Earth as Pink Diamond's colony, and, due to being unaware that the Cluster is bubbled, is visibly saddened by the fact that the planet will eventually be destroyed.

Additionally, Blue Diamond seems not to understand humans, given by how she was surprised that Greg was able to comprehend and sympathize with her pain of losing a loved one.

Blue Diamond, as shown in the episode "The Trial", is extremely diplomatic. Against Yellow Diamond's wishes, she allowed Steven to continue making his case during his trial, though she did lose her temper when his recounting of events differed. She nonetheless seemed to want to hear Blue Zircon's theory on how and why Pink Diamond was shattered. When Yellow Diamond snaps and poofs both Zircons present at the trial, Blue Diamond confronts her and scolds her for not having enough restraint to hear the case out. This shows that Blue Diamond may be as merciful and forgiving as her gems claim – at the very least, she certainly has a greater respect for due process and an interest in the truth.

Appearance
Blue Diamond, as one of the rulers of Homeworld, is of a massive size, her height making a common Pearl pale in comparison. Her complexion is sky blue, and she has alice blue hair. Her hair comes together in the front to reveal her gem. She has a gaunt face, full lips, and a straight nose. She also possesses large, sad, slanting eyes, light blue irises, diamond-shaped pupils, thin, black eyebrows, and three black markings on the lower portion of her eyes resembling eyelashes. Her gemstone is located on her chest, and she wears a long, navy blue cloak. Underneath her cloak, she wears a navy blue cowl. She also appears to be slightly shorter than Yellow Diamond, who herself wears heeled boots.

"The Answer"
After Rose Quartz and Pearl rebelled, Blue Diamond called Sapphire to Earth to share a vision of the future. Once Sapphire explains what the rebels will do on the Cloud Arena, Blue Diamond thanks Sapphire for her vision. Once Rose and Pearl show up, Blue Diamond's Palanquin grows spider legs to get her to safety and protect her. Blue Diamond is later disgusted by Ruby and Sapphire's fusion, threatening to shatter Ruby for fusing with a member of her court.

"Steven's Dream"
Blue Diamond returns to Earth one last time to pay her respects to Pink Diamond before, as she believes, the Cluster will emerge, unaware that Steven had contained the superweapon months earlier. Blue Diamond expresses regret over how she should have done more, and wonders what Pink Diamond would think of the Cluster destroying her colony. After Greg reveals himself, Blue Diamond asks her Pearl to bring Greg to her. She then states how she is impressed by humanity's ability to survive in the wild and remarks on the irony that a fragile human can survive on Earth while a being as powerful as a Diamond can perish. When Greg tells her that he also lost someone close to him, Blue Diamond is surprised that a human can sympathize with her, and is glad that she can save Greg from the Cluster. She forcefully takes Greg and boards her ship with the goal of bringing him to Pink Diamond's Zoo.

"Gem Heist"
Holly Blue Agate reveals that after Pink Diamond was shattered, Blue Diamond took over her Zoo in an attempt to preserve her legacy. Blue Diamond and Holly Blue have been maintaining the Zoo since Era 2 began.

"That Will Be All"
Blue Diamond returns to the Zoo to mourn alongside a room full of bubbled Rose Quartzes. She is shocked to find Yellow Diamond entering the room and tells her that she just wants to cry alone. Blue Diamond listens to Yellow Diamond's song, comforts Yellow when it ends, and is greeted afterward by Holly Blue Agate and the Crystal Gems. Blue Diamond does not understand what Holly Blue means by Sapphire's "special delivery". Once Sapphire lies and tells her that she foresaw Blue Diamond requesting more humans for the zoo, Blue Diamond believes her and is sad to announce that there is limited time to retrieve more humans due to the Cluster.

"The Trial"
Blue Diamond and Yellow Diamond both act as judges for Steven's trial. Blue Diamond first appears beside Yellow Diamond after her Pearl introduces her. She wonders where Rose Quartz is, and when Yellow suggests shattering Rose just for "looking like that", Blue Diamond says she wants to hear her make her case. She also states that she wants to punish Rose for what she did to Pink Diamond. After listening to the prosecuting Zircon's case, Steven tells the Diamonds that he shattered Pink Diamond, prompting Blue Diamond to ask Steven how he did it. Steven doesn't know how so he makes up a story, but when he brings up the Breaking Point, Blue Diamond loses her composure and causes the whole room to cry. She states that Rose shattered Pink Diamond with a sword. After the court takes a short recess, the defending Zircon presents evidence that shows Rose couldn't have shattered Pink Diamond, which surprises Blue Diamond. Eventually, the defending Zircon unintentionally accuses the Diamonds of being capable of such a thing, shocking Blue Diamond. When Yellow Diamond poofs both the prosecuting and defending Zircon, Blue Diamond yells at her to stop, asking her to restrain herself. Immediately after, she is surprised when Steven and Lars hijack her palanquin and escape through the ceiling.

Abilities
Being a Diamond, Blue Diamond is one of the most powerful Gems in the entire Gem Empire. Due to her large size, she is able to lift up a human, such as Greg, with relative ease.

Unique Abilities

 * Radiated Pathokinesis: When Blue Diamond is overwhelmed with sadness, she emits a blue aura around her that induces the said emotion to anyone exposed to it. The induction is powerful enough to cause Gems exposed to the aura to cry immediately unprovoked. The ability does not seem to affect non-Gem beings, as Greg and Lars were not affected by it. It also affects Steven since he is a half-Gem. It's unknown if this is limited to sadness or if she can do something similar with other emotions.

Sapphire
Sapphire was once an aristocratic member of Blue Diamond's court. She was valued dearly for her ability to see into the future. She appeared to talk frequently with her, by Sapphire's words. Blue Diamond went as far as to sentence Ruby to be shattered just for fusing with her, which resulted in Sapphire immediately fleeing the scene with Ruby and terminating her relationship with Blue Diamond. Curiously, after meeting again over 5,000 years later in "That Will Be All", Blue Diamond does not remember or recognize Sapphire from the Cloud Arena.

Blue Pearl
Blue Diamond has her own Pearl, assumed to be her servant. Not much is known about her, in part due to her quiet nature, but in "Steven's Dream", she exhibits great loyalty and respect towards her Diamond and follows her every command, only speaking herself when addressed.

Pink Diamond
"Yellow, she made them. This is all we have left of her. These Gems, this place, and the Earth."

Blue Diamond describes her past relationship with Pink Diamond as very close and still grieves for her thousands of years after Rose Quartz shattered her. In his dreams, Steven saw Pink Diamond's abandoned Palanquin where Blue Diamond knelt down and wept over her passing, which led him and Greg to seek out the location and find Blue Diamond there. Blue Diamond cares deeply about protecting Pink Diamond's legacy, causing her to take Greg to Pink Diamond's Human Zoo in space so that one more human can be saved before the Cluster destroys the Earth. Following Pink Diamond's shattering, Blue Diamond took over operations of the Zoo in an additional attempt to keep her memory alive, where she preserved all the remaining Rose Quartz gemstones in bubbles, contrary to Yellow Diamond's wishes, due to Pink Diamond's role in inventing the Gem type.

Yellow Diamond
"Why can't you just let me grieve?"

Due to their roles as the Gem Matriarchs, Blue and Yellow Diamond treat each other with respect, considering themselves equals. However, Pink Diamond's shattering is a source of friction between them, as Yellow and Blue Diamond have been arguing for centuries over their different ways of coping with her death. Despite their differing beliefs, they still care about each other, as when Yellow nearly broke down after singing "What's the use of feeling, Blue?", Blue comforted her by placing a hand on her back. Their attitude toward legal matters suits their roles as overruling authority figures. Yellow Diamond is a militant considering trials as pointless and would prefer unhesitating action while Blue Diamond prefers to hear every opinion possible to determine the best possible decision even through slow, lengthy processes. It results in a dispute between the two that allow Steven and Lars to escape in Blue Diamond's Palanquin.

Holly Blue Agate
While the full extent of their relationship is unknown, it can be assumed that she trusts Holly Blue, as she gave her supervision over the Zoo, since Blue takes anything related to Pink extremely seriously, this shows the amount of trust she has in her.

Ruby
To Blue Diamond, Ruby is nothing more than one of the common and insignificant soldiers under her command. When Ruby accidentally fuses with Sapphire, Blue Diamond immediately decides to shatter her gemstone as a punishment, even though the unexpected fusion saved Sapphire from the rebel attack. Like Sapphire, after meeting her again over 5,000 years later in "That Will Be All", Blue Diamond does not recognize Ruby as the one who fused with a member of her court.

Steven Universe/Rose Quartz
"My dreams... I was seeing through her eyes! I've been crying her tears!"

Despite not knowing his existence, Steven has an emphatic connection with Blue Diamond that allows him to feel her grief about Pink Diamond. This behavior may be the result of feedback between Steven's empathy and Blue Diamond's own pathokinesis. He also overhears her conversation with Yellow Diamond on how to cope with Pink Diamond's death, which is related to his experiences with Pearl.

Seeing Steven as Rose Quartz, she feels nothing but scorn and wants to inflict the worst punishment possible upon Steven. Despite this, however, she shows restraint and mercy, even going as far as to host a trial to gather the information on how "Rose" shattered Pink Diamond before his sentence. During the trial, Blue Diamond showed frustration and grief afterwards when Steven incorrectly recounted Rose Quartz's crime and showed shock at the revelation of a Diamond possibly being responsible.

Greg Universe
"You know, I really shouldn't be here, but I'm glad I came back one last time. I can save one last piece of her legacy."

Upon encountering Blue Diamond mourning by Pink Diamond's Palanquin, Greg approached her, and the two started talking. In their conversation, they were able to form a connection through their shared understanding of the loss of a loved one, with Blue Diamond and Greg missing Pink Diamond and Rose Quartz respectively. However, Blue Diamond later resolved to kidnap Greg as a last resort to honor Pink Diamond's memory and took him away in her spaceship. Blue Diamond found it surprising that a human could not only understand her pain but also relate to it.

Trivia

 * Blue Diamond is the first of the Diamonds to be seen on-screen in an episode of Steven Universe.
 * However, Blue Diamond was not the first of the Diamonds to be revealed in Steven Universe media as a whole. The extended theme song reveals Yellow Diamond.
 * Despite being a Diamond like Yellow Diamond, the cut of her gem does not exactly match her yellow counterpart, in contrast to most other Gems of the same type. However, since the two episodes they appear in were storyboarded by different members of the crew, their gemstones may only look different due to the differing art styles of the crew members, as they appear to be of the same design – a rhombus-shaped decahedron with a rhombus facet and four rectangular facets on the sides.
 * When she appears for the second time in "Steven's Dream", Blue Diamond's gemstone now bears a closer resemblance to Yellow Diamond's.
 * Blue Diamond's importance is further emphasized, as she has her own palanquin with a curtain in the front and spider legs to move it around on its own.
 * Rebecca Sugar has mentioned that blue colored Gems are mainly diplomats.
 * Rebecca stated that Blue Diamond's character design is meant to look "ghostly" to get the feeling of her mourning, and draws much influence from Martha Graham's Lamentation ballet dance. Her face and hair designs are also inspired by Leiji Matsumoto's art, to make her come across as a "strange presence."
 * Much like Ruby and Sapphire before "Hit the Diamond", all Blue Diamond and Yellow Diamond's main appearances have been in episodes featured in a StevenBomb.
 * According to her mural, Blue Diamond ruled over nine planets when the Moon Base was built. It is currently unknown how many more she might rule.
 * Many Gems under Blue Diamond have similar gemstone designs (wider at the bottom, tapering to a point on top), reminiscent of a teardrop shape.

Cultural References

 * Blue Diamond's appearance and her throne appear to be heavily influenced by Indian and Muslim culture. Her clothing resembles that of traditional Arab wedding dress, specifically a Henna dress.
 * The frame of her throne has carved geometrical designs for windows, which are a common design in many Indian temples and houses.
 * The largest blue diamond, the Hope Diamond, also originates from India.

Gemology
Gemstone Information
 * Diamond is the official modern birthstone for April, and it is also used as an official sixty-year anniversary gemstone.
 * Diamonds are the stone of truth and victory.
 * It is associated with lightning and fearlessness, and for its properties of protection.
 * The diamond, in its rarity and beauty, is a symbol of purity and innocence, love, and fidelity, and embraces the strength of character, ethics, and faithfulness to oneself and others.
 * Diamond is the transparent, gemstone-quality crystalline form of carbon and it is indeed one of the hardest known natural substances on Earth.
 * Diamonds' hardness is the result of adamant chemical bonds between the carbon atoms.
 * There is no other gemstone in the same family as diamond, although there are a variety of very similar gemstones.
 * Diamond is pure carbon and is chemically the same as graphite.
 * Although traditional colorless or "white diamonds" are by far the most famous colored diamonds, yellow and brown diamonds are the most commonly occurring diamonds.
 * Other diamond colors include pink, red, orange, yellow, green, gray, and black.
 * Specific colors will trade under specific names.
 * Brown and yellow diamonds are often referred to as "champagne" or "cognac" diamonds.
 * If a diamond's impurities consist of boron and low level of nitrogen, the diamond will be a blue or gray color (Type IIb). Other blue diamonds are unrelated to boron; nickel or high concentrations of hydrogen are the likely causes of blue color in some diamonds.
 * The diamond is a p-type semiconductor.
 * Diamond deposits are found worldwide, the most notable being Africa, Australia, and India.
 * Approximately half of the world's diamonds come from Central and Southern Africa.
 * Canada has recently become a primary commercial source for fine white diamonds.
 * One of the most famous diamonds, the Hope Diamond, is a blue diamond and is one of the largest diamonds ever to be cut and faceted. It is known notoriously for supposedly being cursed, depicted to bring forth misfortune to whoever attempts to wear it.
 * A notorious New Age scamming site, The Council of Love, utilizes the blue diamond as a symbol of the Virgin Mary, which may have inspired Blue Diamond's aesthetic similarities to the figure.
 * Blue diamonds represent peace, spirituality, and good health.

Gemstone
Blue Diamond Diamante Azul Diamant Bleu Niebieski Diament Diamantul Albastru Голубой Алмаз