I have purchased CZ earrings before...these are definately excellent quality. They look like real diamonds in every way without the imperfections.  Now, the post is rather large [not too unlike the starter earring post] and hss a good notch in it so the back stays in place for sure.
As for the CZ itself, oh, I'd say it's around one carat in size/each.

PROS: good buy
CONS: none

Happy Shopping!