Escarcha means frost, the kind of frosted dew that forms on leaves and other things. No specific English word for this?
With this piece I made today, I wanted to imitate the texture of frost on leaves. I had a sketch and the idea to have a layer of opal enamel fired just to givrer (French term that we used in school and that only just now, when I translated it, I realized it means exactly escarcha o_O maybe then I should call this piece givrer instead) to give this appearance. But later on it ocurred to me to add pulverized mica to the enamel to get the shimmer effect of frost. I made some tests beforehand and it turned out right (mica that I ground with silver flux and white opal), so I used it on my piece, too:
I got ice-flake (cracked) quartz beads to go with this one. They refract the light in rainbow, but it is not apparent in the pictures. It is also difficult to capture the shimmer of the mica so I made an attempt at an animated gif:
You will have to click, I know how annoying looped gifs can get ;P