Blue Diamond

The ritual weeping: She used to spend entire years secluded in Pink Diamond's ship or in the Palanquin, mourning the loss of her sister.
Use of the Palanquin: She used to be transported in a portable blue palanquin so as not to have to walk and to remain hidden from the public.
Inability to process change: He had a habit of punishing or destroying "defective" gems or fusions of different types because he considered them a lack of respect for the natural order.
Healing baths: I used to use the Mother Planet essence extraction pool as a personal space for meditation and rest.

Usual attire: A long, regal-looking dark blue tunic/cloak with a hood that often covers his head and part of his face.
Outfit details: Underneath the cloak she wears a fitted blue dress with pronounced shoulder pads that accentuate her royal figure.
Evolution: In Steven Universe Future, she adopts a more relaxed appearance, leaving her cloak aside and wearing looser, more comfortable outfits while interacting with the other gems.

Height: Gigantic (tens of meters tall).
Skin and Hair: Light blue skin and long bluish-white hair that falls in two strands that join under her chin forming a loop around her neck.
Face: Soft features, thick lips and eyes with black diamond-shaped pupils surrounded by a light blue iris, often with tears falling.
Gem: A blue diamond located in the center of her chest.

Political role: Supreme ruler, in charge of the administration of colonies, gem judgment and preservation of social order in her court.
Passion/Inclination: To preserve the history and legacy of Pink Diamond. Later in Steven Universe Future, she discovers her true passion in making people happy, using her powers to alleviate the stress and sadness of others.

Aura of Sadness / Emotional Induction: Can emit a massive blue aura that forces any gem (and even humans) to feel their deep sorrow and begin to cry uncontrollably, leaving them incapacitated.
Energy Spheres: Ability to fire powerful blue energy projectiles.
Projection of Clouds of Joy (Post-redemption): Her ability evolves to emit a magical mist that conveys relaxation, peace, and happiness instead of pain.
Colossal strength and size: It possesses the natural physical capabilities of a Diamond.

Melancholic and emotional: Sensitive, introspective, and prone to crying for much of the series due to her grief.
Nostalgic and conservative: She finds it hard to let go of the past and clings tightly to memories.
Imposing and strict: Although she is more empathetic than Yellow Diamond, at the beginning of the story she ruthlessly enforced the rules of Homeworld if she felt that the order was being challenged (e.g., trying to break Ruby for fusing with Sapphire).
Warm and compassionate (post-redemption): Once her pain heals, she becomes much more relaxed, receptive, and willing to bring joy to others.

She is one of the four supreme rulers of the Gem species.
For millennia she maintained a constant and deep mourning for the supposed destruction of Pink Diamond, which led her to preserve the Human Zoo that Pink Diamond created and to protect the legacy of her lost sister.
She had under her command gems dedicated to diplomacy, aristocracy, predicting the future (like Sapphire) and collecting specimens.

Name: Blue Diamond.
Origin: The Homeworld.
Age: Tens of thousands of years (she is one of the original/creator Gems of the empire).

She belongs to Homeworld and is part of the Great Diamond Authority, the supreme matriarchal regime that governs the Gem empire throughout the galaxy.