the screw backs on these have not loosened or given me any issues. i have worn them a few weeks now without any issues with the backs.  they were had a ton of sparkle in them when i got them. when i ordered them i was a little afraid the size might be a little "iffy" to be believable but they look good. as i said i have worn them continuously for a few weeks and they so not have the super sparkle as when they were new but they still look great, they are not dull or cloudy at all, but almost more believable now. i am very happy with them.