Wow, thank you. Love the detail on your work. Would never of thought of using coal dust! When I think about it why not? It is a mineral, hard and I can see it polishes up well-must give that a go.
You say you finished your work down to 600 grit, did you seal your work first, before filling ? My guess is you did, but I may be wrong.
I have just tried mixing epoxy resin and mica powder and like you have discovered, it works. What I find exciting about mica are the vibrant colours. I plan on making some turned bangles with my students, possibly segmented. I hope to use mica to embellish their work. I think they will love decorating it like your feature ring and then polishing it to a shine.
Do you mind if I show them your pics? What a shame you can't show it to them and talk about it-inspirational!
Thanks Woody