This cab is a metallic blue mica on top of a black resin.
Hand painted and hand poured, in a handmade mold.
Based off of Vintage Glass Cabochons, created in the 1960's, they are a textured cab that I'm sure they didn't intend to look like a brain, but that's exactly what I thought of when I saw them, so, of course, I had to mold them!
This cab measures 25x18mm.
It has a textured top, and a relatively flat back (easy to adhere).