This looks too good to be true. I am interested in this (because of all the terrible stuff related to diamond mines), but how do you protect yourself from scams

This looks too good to be true. I am interested in this (because of all the terrible stuff related to diamond mines), but how do you protect yourself from scams on this site? $500-$1,000 is a lot to "test the waters" and see if they are real or even if they will arrive. What is the chance the just swap it out with Moissanite or who knows what?