can anyone help
is it possible to pickle a ring set with a garnet stone
set in 22ct gold on a 925 silver ring
as I like the white look of silver after it has been pickled?

Yes, just so long as you don't do it while it's hot.

if so are there any stone's that can not be treated this way
many thanks

Yes, any number of them. Just a couple off the top of my head would =
be
torquoise and coral.