|This article is about the character. You may be looking for the instrumental song.|
I'm surprised that a human being is capable of understanding how I feel.
As shown in her debut, Blue Diamond is portrayed 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. This is demonstrated when she "saves" Greg from the threat of the Cluster after taking a liking to him, unaware that the Cluster is no longer active. 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. Albeit, she has a diplomatic personality, wishing to find a compromise rather than to destroy things outright. Her reputation as merciful and forgiving is at odds with her actions. However, she may have changed in the 5,000 years following the death of Pink Diamond.
Blue Diamond is currently in a state of great depression, having mourned the loss of Pink Diamond for thousands of years after her shattering. She is unable to let go of the past, clinging to every reminder of Pink Diamond she can. When it comes to things that used to belong to Pink Diamond (For example, the Earth), she considers them to still belong to her. She even audibly ponders what she would have thought of letting Yellow Diamond put the Cluster in the Earth. If the situation requires it, Blue can hold it together for her subjects.
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, and while she considered it a shame that Earth would be destroyed by the Cluster, she does not appear to intend to do anything to prevent it.
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 light blue, and her hair is a very pale shade of blue, appearing as off-white. 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 and quite thin by comparison.
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.
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.
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.
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.
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 Diamond has her own Pearl, assumed to be her servant. Not much is known about her, in part due to her silent 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.
Yellow, she made them. This is all we have left of her. These Gems, this place, and the Earth.
|—Blue Diamond, "That Will Be All"|
Blue Diamond describes her past relationship with Pink Diamond as very close and still grieves for her thousands of years after she was shattered by Rose Quartz. 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 Earth is destroyed by the Cluster. 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.
Why can't you just let me grieve?
|—Blue Diamond, "That Will Be All"|
Considering 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.
While the full extent of their relationship is unknown, it can be assumed that she trusts Holly Blue wholly, 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.
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. Similarly to 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 Sapphire.
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.
|—Blue Diamond, "Steven's Dream"|
When confronted with 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.
|1. "Full Disclosure":||Absent||14. "Historical Friction":||Absent|
|2. "Joy Ride":||Absent||15. "Friend Ship":||Absent|
|3. "Say Uncle":||Absent||16. "Nightmare Hospital":||Absent|
|4. "Love Letters":||Absent||17. "Sadie's Song":||Absent|
|5. "Reformed":||Absent||18. "Catch and Release":||Absent|
|6. "Sworn to the Sword":||Absent||19. "When It Rains":||Absent|
|7. "Rising Tides, Crashing Skies":||Absent||20. "Back to the Barn":||Absent|
|8. "Keeping It Together":||Absent||21. "Too Far":||Absent|
|9. "We Need to Talk":||Absent||22. "The Answer":||Flashback|
|10. "Chille Tid":||Absent||23. "Steven's Birthday":||Absent|
|11. "Cry for Help":||Absent||24. "It Could've Been Great":||Pictured & Mentioned|
|12. "Keystone Motel":||Absent||25. "Message Received":||Absent|
|13. "Onion Friend":||Absent||26. "Log Date 7 15 2":||Absent|
|1. "Super Watermelon Island":||Absent||13. "Kiki's Pizza Delivery Service":||Absent|
|2. "Gem Drill":||Absent||14. "Monster Reunion":||Absent|
|3. "Same Old World":||Absent||15. "Alone at Sea":||Absent|
|4. "Barn Mates":||Absent||16. "Greg the Babysitter":||Absent|
|5. "Hit the Diamond":||Absent||17. "Gem Hunt":||Absent|
|6. "Steven Floats":||Absent||18. "Crack the Whip":||Absent|
|7. "Drop Beat Dad":||Absent||19. "Steven vs. Amethyst":||Absent|
|8. "Mr. Greg":||Absent||20/21. "Bismuth":||Absent|
|9. "Too Short to Ride":||Absent||22. "Beta":||Absent|
|10. "The New Lars":||Absent||23. "Earthlings":||Absent|
|11. "Beach City Drift":||Absent||24. "Back to the Moon":||Pictured|
|12. "Restaurant Wars":||Absent||25. "Bubbled":||Absent|
|1. "Kindergarten Kid":||Absent||13. "Gem Heist":||Mentioned|
|2. "Know Your Fusion":||Absent||14. "The Zoo":||Mentioned|
|3. "Buddy's Book":||Absent||15. "That Will Be All":||Appears|
|4. "Mindful Education":||Absent||16. "The New Crystal Gems":||Absent|
|5. "Future Boy Zoltron":||Absent||17. "Storm in the Room":||Absent|
|6. "Last One Out of Beach City":||Absent||18. "Rocknaldo":||Absent|
|7. "Onion Gang":||Absent||19. "Tiger Philanthropist":||Absent|
|8/9. "Gem Harvest":||Absent||20. Room for Ruby":||TBA|
|10. "Three Gems and a Baby":||Absent||21. "Lion 4: Alternate Ending":||TBA|
|11. "Steven's Dream":||Appears|
|12. "Adventures in Light Distortion":||Mentioned|
- 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. Yellow Diamond was revealed in the extended theme song.
- Despite being a Diamond like Yellow Diamond, the cut of her gem does not exactly match her yellow counterpart, in contrast to other gems of the same type, who appear to share color and cut. 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 a lot of 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.
- 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.
- 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.
|Blue Diamond's gemstone is located on her chest, featuring a diamond-shaped facet, and a diamond shape overall.|