These are acrylic faux shell 18x13mm cameos in a darker color, almost carnelian.  I've surrounded them with size 13/0 Charlotte Cut glass beads with the gold ones being 24K gold.  Backed with genuine pigskin suede leather and  currently hung from 14K gold fish hook ear wires.

I can convert these to clip-on, posts, or lever back, just contact Sunshine for your custom order needs.