Dead corals for display in freshwater aquarium

Hi Prof

I understand that corals affects the ph and hardness. How can one preserve dead corals for purpose of display in a freshwater aquarium? Can one paint them with an epoxy? They are white (since they are dead). Do you know products that can be used to artificially restore their color and make them inert?

Should I get someone to cast it in a tranlucent epoxy?

Regards
Gerrit