Wholesalers don't sell outside the trade. So if he was not within the trade, he really didn't get them "wholesale." But jewelry is NOT an investment. Appraised value in the terms you are discussing are related to insurance replacement value, and not resale value and what you paid for it generally means nothing when it comes time to resell. Much like a car, diamonds kind of depreciate once you "pull out of the lot" which, while I agree is insane, is kind of the way it goes, since dealers can usually get brand new goods which they can confirm the history and provenance of for less than they're going to pay you for your preowned item, which they cannot confirm the history and provenance of. Unless you have something specific that is uncommon and really in demand, you're not going to get a lot.
You might get the most money by trying to sell your main stone separately from the setting, or try the company AllisonFaye mentioned. They might not offer you more than you were offered locally, but it's worth a shot. Worst they say is no thanks in which case you accept one of the other offers, which are pretty decent for pawn shops.