Making gems has stopped me from attempting many a costume in the past, but I was determined to figure it out this time. Raven's belt will not be the most time-consuming part of the costume, but it will be the most detailed. I thought that, if I was lucky, I might find some really big rhinestones. (Who knew that they were in such small supply?) As I was browsing the craft store for inspiration, my sister remarked "It's too bad you can't cut a Christmas ornament in half."
And then it hit me! We went to the Christmas supplies, and, sure enough, there they were--smooth Styrofoam balls! (As opposed to the normal Styrofoam balls that have a bubbly texture.) I've tried two different brands and found them to be exactly the same. They only come in a few sizes, but you have a lot of leeway for gem size depending on where you cut.
Step One is to slice those suckers in half. They even have a convenient ridge to follow. Any decent-sized cutting implement ought to work; I just used a steak knife and got a relatively clean edge. (The edges don't really matter, as they are covered up later.) While you are cutting these, resist the temptation to pull them apart once you're almost all the way through. Slice the whole way down; otherwise, a chunk of foam may detach, and your gem will have a hole.

Speaking of holes--the result will be one nicely smooth half and one half with a round indentation. (I suspect that this is for the attaching of hooks to make Christmas ornaments.) You can discard the dented half and only use the smooth side. Since these are pretty cheap, it's not an unreasonable idea. I filled in the indentation with spackle, then sanded it down smooth and painted over it. (I happened to have spackle on hand, but a more logical choice would be clay, putty, or any sort of gooey substance that will harden without the help of an oven.)
Next, these need paint. I used three coats of Folk Art's #437 (Lipstick Red). Painting the entirety of something you are trying to hold can pose a problem; I solved it by holding the half-balls with a plastic fork stuck into the flat side. Just pop them off (carefully) and lay them down to dry.
After painting, the colour on the gems looked great, but they became dull once dry, so I sprayed them with triple-thick gloss. (I keep this on hand to seal my Dungeons and Dragons miniatures after painting.) Nice and shiny! I highly advise letting these dry overnight before continuing. If you're really into detail, you can paint highlights and shadows on the gems before sealing (though I don't think they need it).

While the paint and gloss was drying, I invaded my mother's craft supplies again, borrowed her circle cutter, and made a paper circle a bit bigger than the styrofoam domes (about two or three millimeters sticking out on each side). Using the paper as a pattern, I cut out circles from a sheet of black craft foam using an Exacto knife. These circles do not need to be perfect, as (ideally) they will not be seen, so don't worry if you don't have access to a circle cutter.
If you don't feel like putting as much detail into the gems, you can use yellow foam to serve as the gold setting. I used black so that, if any of the foam should somehow show, it will blend in with Raven's black leotard. One sheet of foam ought to be plenty enough for this project.
Once my "clown noses" (as my parents called them) had dried completely, I hot-glued them to the centers of the black foam circles.
Next comes the gold setting. On Raven, the gold is usually drawn rather wide; however, I feel that a thick gold border would look silly on a real person, so I bought thin gold trim. If you want a thicker setting, it would be easy enough to sew cord out of metallic fabric. Cut off an appropriate length of the cord, then hot-glue it to the black foam around the edges of the Styrofoam. This will conceal the black foam and the edges of the Styrofoam.
Voila! A gem is complete!

These can be attached together several ways. The easiest method would be hot-gluing them all along a long piece of the gold cord; however, I wouldn't trust this not to fall apart on me. I've seen some people use chain to connect the gems on Raven's belt, but I don't feel that this is accurate to the character design. I cut 2 1/2-inch strips of the cord and sewed them to the gems with gold thread. (You will need a thimble for this.)

Once the belt is the proper length, make sure that each end has a strip of cord on it (not a gem). Choose your fastener; I used a small hook-and-eye fastener. Since Raven wears her belt higher on the left side, I will add a small loop on the leotard to keep that end of the belt up. (I know, the picture is crap.)

I recommend giving the belt the "swing test" (spinning it around on your arm to make sure it won't fall apart) before pronouncing it done. As far as I can tell, my belt has the same number of gems that Raven's does. You may need to add or subtract depending on the size of your waist.
Costume status:Cloak
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Wig
ChakraLeotard
Gloves
BeltTights
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