Steven Universe is a great show. Great enough that I got inspired to make an OC for it. As silly as it feels to do so.
Steven Universe, so far as the gem species that forms its main cast go, present some problems from a fan character perspective; for one thing, there are the usual issues with making OCs, but these aren't so bad given most gems are off in space, and presumably spread wide across the universe, which makes finding a "place" that's both not stupidly irrelevant and not shoved anywhere near canon characters easy. More importantly, there aren't all that many gems to base a character on. I chose Tsavorite as a gem prior to doing a casual google of "Tsavorite Steven Universe," but I never really expected it to be unclaimed, and indeed, there were a number of immediate OC results when I did eventually make the search.
Feeling original can be a bit tricky when there are, by the very nature of the show's presented species, any created gem character is going to have one of a limited pool of names, and after that, a limited pool of corresponding colors. That being said, some of Jasper's comments--namely referring to some of the crystal gems as "an [insert gem here]"--imply that there really are just a bunch of "repeat" gems. And really, it kind of makes the subtle variations more interesting. Or boring, and hard to make matter. Your call. I fall somewhere in between. The concept of making a gem OC feels both stupid and immensely fascinating to me.
And with that little ramble done, a bit about this OC. She's left still uncolored, both because I lack any means to color her (I rarely art, and when I do, never beyond sketches), and because the OC herself is unfinished. She's likely going to be dark green, and I was considering various shades of dark purple for her clothes, with pink or red for her hair. The belts on her clothing are black, as are the stripes (unless they end up being some shade of grey). Her gem is located on her right shoulder--this reflects a lack of balance in her personality. Also, it's not a location I imagined would be all that common, unlike the head, which was my second thought (hell, that's the only spot that's been used twice just in canon). Her weapon is a dark green halberd. She's a strange mix of qualities; laid back and lazy, but inclined toward anxiety and demanding of strict order in things. Admiring of nature, other life, and simple experiences, all of which other gems find pointless (things like eating, sleeping, and native fauna), but immensely fond of the gem homeworld and fully supportive of their action in the universe. I imagined her job as either being some form of scientist--an engineer or biologist especially--or a doctor, or a disciplinary officer/law enforcer. Not really that decided on things, as should be clear.