This is when they take a gold (white or gold) I believe and re-dip it to add back to the finish…over the years gold wears and the rhodium you can re-do and put back the shine.

Rhodium is a metal in the platinum family. By plating any base, including sterling silver, in rhodium, pieces will not darken and tarnish.
It is a member of the platinum family and is used as an overlay to prevent irritation from another metal that might be prone to cause irritation.

Rhodium is a by-product of platinum. When layered over SS, it prevents the sterling from oxidizing and tarnishing–that’s the main benefit to me, I do not want to polish my SS jewelry. I also have my 14K white gold wedding ring and engagement ring rhodium-coated annually to brighten it up and make the white really glisten as well.