Rasesh, Even though you are not casting your stones in place, I am
sure you can solve most of your problems by correcting the master
models. If your designs do not have structural integrity then any
flexing of the ring can cause stones to pop out. Also you may not be
using enough material for the settings to hold up to normal wear and
tear. If you can email me photos of one of the problem rings I might
be able to help.