I'm not certain what sort of you are after, but I do know
something about this. Though my experience is in an "industrial"
application (Thin film optical filters) rather than jewelry, the
general processes would be similar, I suspect.
In general terms, CVD and "plasma deposition" describe two somewhat
different processes. Feel free to email me directly, maybe I can
answer some general questions, or maybe not.
Glad to try, however.