Undrilled round glass beads. The opaque colors look like tiny pearls.
Add to a tiny bottle, like the Iridescent Glass Spheres linked below,
or float in ICE Resin, or use glue or double-stick tape to adhere to
Sold per 15-gram vial, which is about a zillion beads!
And see below for a quick pic on a cold Winter's day (you can, at least, see the size of the vial).
Design Team Member Nichola Battilana made A Tale of Underwater Love (see the wide photo below). More info in the blog.