I dread these questions:-) I know nothing about jewlery and I get given jewlery and I have had these a while now and don't use clip ons. I think they were given and I was told they were too good for Goodwill or a garage sale, if I remember; for what that's worth. Sorry.
Hi, the earring were made circa 1940 - 1950 the black stone is a natural black rock crystal called Jet, or basically black glass, and the white stones are paste or rhinestones set in pot metal or soft white metal, if this piece was real the earrings would not have been made with a clip-on attachment it would have been made to secure to the ear and not to come off, pull off, or catch on a collar and fall off, unless purposely taken off ie, screw w/lock, pierce or in the period of Marie Antoinette they would have been made to clip and a secure piece for the inner part like a weight so the earring made or real jewels would clamp and hold and you would not be able to pry or bend the prongs to pop out the stones.......
Very pretty. I like clip ons. They are fast and easy for my mom who has arthristis in her hands. She can not get regular pierced errings on, but the clipons are just fine for her to dress up for Sunday. Thanks for offering these.