I will be interested in the responses you get from your question
myself, because from my own experiences, I avoid rhodium whenever
I bought a small manufacturing company more than twenty years ago,
and at that time, all white gold products we made were plated.
Gradually, over the years, and for a multitude of reasons, we do
absolutely no plating of our white gold. Just one of the reasons is
the very one you mention, that customers become very upset when the
color of their jewelry changes over time, and unless you
electro-strip the old rhodium off, the replating job looks bad.
Sizing a ring is a problem, which may be the reason your customer’s
ring turned yellow on the bottom.
I got rid of the dangerous chemicals many years ago, and would never
go back to that mess. I believe that once or twice, over the past
ten years, that we have had an occasion where a customer has
requested a piece be plated, and we just sent the item to a local
trade shop to have it done for them. I have had many more customers,
when ordering a white gold piece, request that no rhodium be used.
Just my own views on the subject, but wondering how others feel, Jon