Red Diamond has red-pink skin, plump lips, and red hair with swirling bangs and is also tucked into her top. She has a thin build, large hands, a thin waist, and moderately wide hips. Her gemstone is embedded in her navel.
She has a maroon V-neck shawl-like top with red-pink layered underneath. She has loose-fitting rounded sleeves with wrist-fitting dark maroon bracers. She has a translucent pink veil that connects to both of said bracers. She has a dark maroon waistband which connects to a hip-fitting, floor-length layered maroon dress.
Her current outfit is almost the exact same as her previous design. She has a maroon V-neck shawl-like top with red-pink layered underneath. She has loose-fitting rounded sleeves with wrist-fitting dark maroon bracers. She has a dark maroon waistband which connects to a hip-fitting, floor-length maroon gradient dress.
Red Diamond may be fairly new but she’s striving to be her own Diamond, rather than Pink Diamond's replacement. She's been rushing and colonizing planets so she’s a bit unorganized at the moment. She's described as being a lot stronger than Blue Diamond and Yellow Diamond, as well as her and Yellow not liking one another. She is a very stern ruler, though she cares for all gems no matter their status in her court.
Besides that, she's a very kind and curious ruler, she only acts stern, and in the thousands of years since she's come into power she has never shattered a Gem or had one shattered. Now, she understands she will never replace Pink Diamond, so as the other Diamonds.
Red Diamond possesses standard Gem abilities, bubbling, shapeshifting, fusion, regeneration, agelessness, and superhuman strength/durability.
Anger Empowerment: When she's angry, Red Diamond becomes empowered with enough strength to take down another Diamond. Her form completely shifts and she becomes a beast of rage and fire, with a whole different personality. Yellow Diamond is said to show fear when she's at this state, while Blue Diamond is the only one who can calm her down.
Absorption: When she's angry her enhancing powers reverse and instead of giving power, she absorbs power from other Gems. In this state, she'd be able to drain all of Yellow Diamond's strength.
Enhancement: Red Diamond's most noticeable power is the enhancement of other Gems and their respective powers, simply being around her increases the strength and power of all other Gems. If she were to use this ability on Steven Universe, he'd gain easier access to his Gem powers and probably lose control, since they'd drive his gem into overdrive and he'd likely not be able to sustain that. 
Enhancement Beams: She can shoot this ability directly at a Gem and, combined with her aura, boost up their abilities to a very high state.
Pyrokinesis: Red Diamond is able to breathe, control, and manipulate fire.
Fire Beams: A frightening use of her pyrokinesis is emitting beams of flames from her eyes.
Mind Reading: If Red Diamond is able to make direct eye contact with another Gem she will be able to read their thoughts. This ability only works on Gems and would not affect hybrids or organic life forms.
Diamond Luster: Like all Gems, Red Diamond is able to emit light in a concentrated form from her Gem, which can distort another Gems' physical form, but does not affect other Diamonds.
Red Diamond feels bothered about being Pink Diamond's replacement, especially with how Blue Diamond goes on still mourning Pink's demise. Blue was the only Diamond that really showed Red Diamond some compassion, but at the same time, she also makes her feel inadequate. Blue Diamond is the only Gem she really clicks with.
She has six half-completed colonies, intentionally delaying their progress to preserve their natural beauty.
One of them, Ni'vallah, is the home for multiple organisms, and is very similar to Earth in composition, but still bigger than the planet.
It took one or two hours for GemCrust to draw it.
One of Red Diamond's previous planets had a previously unknown species living deep within the planet's crust, only to be awakened when the Kindergartens reached the right depth. They destroyed a few Gems, and were a tenacious species of alien proving to be somewhat difficult for the Quartz soldiers. Red Diamond, cycles later, checked upon that colony to see if the species had been dealt with.
Since Violet Diamond was made before she was, Red Diamond doesn't know of her existence, along with Blue Diamond.
Red Diamond finds Pink Diamond's Human Zoo intriguing but not something she herself would do. It's not that she doesn't like organic lifeforms, she could understand preserving certain lifeforms for study but keeping them for entertainment or just to keep for the sake of keeping is a waste of resources.
When Red Diamond came to Earth, she really liked the red roses that grew here, and she also took someone's red car thinking they were what the humans call pets.
Red Diamond is more powerful than Pink Diamond.
GemCrust stated that, if Red Diamond were in "That Will Be All", she probably would have sung along with Yellow Diamond, but telling Blue Diamond that it’s okay to grieve and it takes time before you can move on.
Diamond is a traditional birthstone for April, the zodiacal stone for Aries and Taurus and the tenth and sixtieth anniversary stone, also being the traditional stone on an engagement ring.
Diamonds have a Mohs hardness of 10 and are considered the hardest minerals on Earth, being able to cut glass cleanly.
Diamonds are formed in about 35 countries. South Africa, Russia, and Botswana are the main producers of diamonds while Australia produces most of the industrial diamond. They are also found in India, Russia, Siberia, Brazil, China, Canada and the United States.
Diamonds are formed at high temperature and pressure at depths of 140 to 190 kilometers (87 to 118 mi) in the Earth's mantle. Carbon-containing minerals provide the carbon source, and the growth occurs over periods from 1 billion to 3.3 billion years (25% to 75% of the age of the Earth). Diamonds are brought close to the Earth's surface through deep volcanic eruptions by magma, which cools into igneous rocks
Although white is the most commonly occurring color, diamond is available in a veritable plethora of colors, such as red, orange, yellow, green, blue and purple, even brown and black.
Diamond rarely occurs in color-change varieties, which have a different color depending on whether they are viewed in incandescent or natural light.
Color change diamond is called a chameleon diamond
Diamond is a polymorph of the element carbon, and graphite is another. Because of this, diamond only has a chemical formula of Carbon (C)
Diamond is one of the few minerals that's only in the native element group.
Diamonds are associated with longevity, balance, clarity, intensity, success, and abundance
It also brings eternity, purity, and high-frequency energy.
It also is a stone of amplification, including thoughts, strengths, and weaknesses.
One famous diamond is the Hope Diamond. One of the most famous and valuable jewels in the world.
The powder of a diamond is often used industrially, the small crystals being used as cutting aid to cut and facet other tough minerals, and saw through metals.
Diamonds cannot be scratched or cut by anything other than diamond itself. However, if a diamond is pressured just right, it will shatter.