If I have a stone, and then I get a LOGR halo setting to fit it - what is a reasonable amount to expect to pay to have the stone set? How long should it take? And, what should I "watch out" for? There are a couple of places near where I live who can do this but no one wanted to give me a rough idea how much it would be until they saw the setting (though I explained it was a 4-prong design w/ a halo).