Try using white vinegar I have not used it on vintage pieces, but
I’m sure it wont do any harm.
In my experience vinegar cleans crystal, silver and glass like
nothing else. If you are a coffee drinker you will be familiar with
the foil wrapped bags that package your coffee grains. Wash thurily,
and then add clear white vinegar, fill it to about quarter full and
then add two table spoons of salt.
Add your crystals, fold the opening of your bag tightly shut, then
holding it together and shake it for a few minutes, basically for as
long as your patience will allow, then remove your crystals and wash
in cold water. You will see them sparkle like never before.