When I worked as an appraiser, I had to deal with this too.
Worse, nasty old jewelry, worn for 50 years, under the microscrope
at 10X magnification!!! Yuck!!! Um. I would just tell them that
I needed to go to the kitchen (ultrasonic there) to clean it, and
that they could come with me if they wanted (if paranoid). I don’t
specifically remember earrings, but I’m sure I kleenexed them (if
could not be ultrasonic’ed) or water cleaned them…
A little dish to recieve these gifts would be good, and a supply
of those First-Aid supply alchol towlettes, individually packaged.
I think if one just made it a practice of cleaning all items upon
taken in (obviously, I mean simple things like cleaning the ear
posts in this cast, without touching the pearls, and I know one
would never clean a piece of jewelry without first inspecting and
identifying all the parts/stones), and if this were done very
matter of factly, without comment, that it would be accepted as
one of those mysterious things jewelers do.
Near Lake Michigan