what are these called?

I've been trying to find a certain type of bead, obviously I'm not
using the right terminology because I've had little luck. I know they
exist because I have a few store-bought bracelets with similar beads,
they must be out there somewhere. ;-)

Okay, here's a description: silver outside, flat-back, with crystal
inside... I have some in round and some squares. The crystal's are
only on one side of the silver "holder", the underside is the flat
silver.

If anyone can tell me what to call them for a search, or even better
direct me to a few websites that sell them, I'd soooo appreciate it!

Thanks
Cindi