christine - yes, there is quite a difference in values of cz material
which i won’t go into here, but my reason for responding is this:
write up a description of what the client has asked you to do. ask
her to be with you when you remove the diamond from her ring. have a
receipt ready for her to sign stating that she received the diamond
from you after it was removed in client’s presence. have her sign it.
then get into the business of replacing a cz into the setting.
on the west coast of florida we have had an ongoing series of suits
about stones being replaced by jewelers - part of which just might be
a scam by the ‘client’.
protect yourself with the above even if it’s your sister.