I own several of these pairs of earrings.  I hadn't bought any for a while and I received these today.  I have to say that the backs seems even smaller although I am not sure that they actually are.  I twist them twice and I can't twist any further.  I don't think that makes them very stable.  I will give them a try but might be searching for new back for them.  Otherwise they are as pretty as I expected.

I am editing my review.  I wore these and a friend asked me if they were cut glass.  Ugh!!  I got in front of a mirror and sure enough, there wasn't as much sparkle as the stones that I have gotten in the past.  I didn't pay that much for them, so I will keep them.  But now I am wary of wearing them again.  I am also still having issues with the backs.  And I wear a plastic discs to keep the earrings upright on my ears.
Addendum:  the backs to these are smaller than the ones I originally bought.  They don't work on any of the earrings I have bought from this seller.  There has to be better backs somewhere.