Neptunite has grey skin with dark navy blue stripes on most of her arms. She has off-white unkempt hair. Her lower face has off-white lips and a visor covering two sets of eyes. Her bottom eyes have bi-colored red and blue irises with black, rhomboidal pupils. Her top eyes both have two more irises, each bi-colored blue and pink and lacking pupils. The face on her forehead has plump lips, a functioning mouth, and two sets of eye sockets which lack eyes.
She has a relatively thin build, other than her large, bi-colored navy and grey abdomen. Her abdomen has four sets of arms, each with an eye, six abdominal eyes of blue, magenta, and green coloration, and one pair of legs. The top of the abdomen has a dark navy star. Her gemstones are embedded in both of her top palms, the center of her back, the center of her face where her nose would otherwise be, her navel, her sternum, the center of her chest, and her forehead, which house Pearl and Peridot's gemstones.
Diverging in tones of violet and magenta, Neptunite wore an apron that covered her chest, pointed blue shoulder pads, and evening gloves on all four main arms. Tying around her waist was a crimson red sash, which connected to her abdomen. Her front two sets of abdomen arms wore pairs of gloves — the first one, magenta, and the second, blue —, while her only set of actual legs wore violet leggings with dark pink boots.
In her reformed form, Neptunite's colors now adhere much more to those of real-life neptunite than they did formerly. One pair of arms, which previously came out from her chest, fades away in this version.
She wears a tri-colored navy V-neck top with pointed dark navy shoulder pads and dark navy gloves on her main set of hands. The top has a lighter navy V, bordered by more navy. She has a black gradient waistband that connects with her abdomen. Her front two sets of abdomen arms wear Ice's armbands, with the second set donning a star. Her only set of actual legs wear dark navy leggings with dark purple boots which are separated by a purple-grey stripe.
Despite being a calming deity, Neptunite is a massive force of unstable power and can only be effective in battle if all of her component Gems work together and focus on the task at hand. She lacks her own individuality.
Neptunite possesses standard Gem abilities, bubbling, shapeshifting, fusion, regeneration, agelessness, and superhuman strength/durability.
There are so many Gems constituting her she's more so a weapon than an actual Gem. With so many minds roaming around in her head, it's difficult for Neptunite to move at all.
Blunt Club: Through combining the weapons of her constitute Gems, Neptunite can form her own, a blunt club, which she can use with skill.
Amalgam Physiology: By extension, she is able to summon the weapons and control the powers of all her components and the fusions within her.
Invisibility: A variation of her components' photokinesis, this ability allows Neptunite to refract light around her to become invisible.
Crystal Thread Creation: Neptunite can weave crystalline thread and make webs, somewhat like a spider.
Psionic Screech: Neptunite is able to emit a noise that can disrupt Gems' physical forms temporarily.
Neptunite is one of GemCrust's favorite fusions of his authorship in terms of design.
When designing Neptunite, GemCrust stuck with the first attempt he did on her. There was no "trial and error."
GemCrust has so far shunned away from drawing Steven Universe's version of Neptunite because the idea of it "makes [him] cringe."
Before he decided on a blunt club as her weapon, GemCrust was leaning toward giving Neptunite either a lance or a trident, the latter to reference the god Neptune — god of freshwater and the sea — from Roman mythology as his name bears similarity to hers.
Her voice is her components' voices layered over one another with a deep echo on it.
Neptunite is a silicate mineral with the formula KNa2Li(Fe2+, Mn2+)2Ti2Si8O24. With increasing manganese it forms a series with mangan-neptunite. Watasumiite is the variety with vanadium replacing the titanium in the formula.
It was first described in 1893 for an occurrence in the Narssârssuk pegmatite of West Greenlands. It is also found within natrolite veins in glaucophane schist within serpentinite in San Benito County, California, US. It also occurs in Mont Saint-Hilaire, Quebec and in the Kola Peninsula of Russia.
The mineral is named for Neptune, Roman god of the sea because of its association with aegirine from Àgir, the Scandinavian sea-god.
The Gemologist Institute of America (GIA) identified an 11.78-carat faceted specimen as neptunite based on Raman spectroscopy.