Vera, Streel shot is much harder than carnelain and will damage it.
For cleaning and polishing those types of pieces, whether gold or
silver or whatever, use crushed walnut shell in a vibratory or rotary
tumbler. You can add a few scrapings of rouge as well. I have been
using the same batch of wlanut shell and rouge for over twelve
years!!! Takes a litle whle but nodamage… You should be able to
get crushed walnut shell (or corn cob) at most lapidary suppliers or
at any gunshop, where it used to reclean and polish
bbrass ammo cartridges. Wayne