I remember looking for a diamond and the gal at the Zales or whatever, said “I can’t believe you would want a used diamond” because I was looking at antique jewelry places too. I said, “hey they’ve been around since the dinosaurs, right?” Bought from the antique jewelry place. Looked at a pawn shop too.
A diamond lasts forever (isn’t that the saying?) A “used” diamond is simply a diamond without a home yet. I have seen some of the antique settings (which are making a comeback by the way) and they are unique and beautiful!