The last time I was in NYC buying supplies, I stumbled across some beautiful"old new stock" broach settings that had obviously been intended to be rhinestone-filled jewelry by some long-forgotten designer. I bought a bag of them and contemplated doing something with resin, but in the end decided to just sculpt wire around them.
There is an old-fashioned safety clasp pin on the back; this would be a beautiful and elegant accent to any outfit, but as it's fairly heavy, it would be best on a fabric without a lot of stretch or drape.