I worked on Jewelers Row in Philadelphia for 10 years in sales, as a buyer of set pieces and loose stones, and designing and organizing the construction of custom jewelry.
“Retail” on jewelry is arbitrary and subjective. What is retail at a jeweler in a competitive jewelry district like Jewelers Row is a fraction of what is retail at stores like Zales or Jared’s, let alone Tiffany, et al. Plus as previously mentioned, what you can get on the resale market is MUCH lower than what you paid for it, period, and when you have people who have been offered scrap value for a piece, they can sell it on a place like Mercari for a steep discount and still make more money than selling to a scrap dealer.
I have since moved to Atlanta and left the business. Just 3 months ago, I had a white gold setting that had 2 excellent quality diamonds totaling 1/3 carat in it which I reset the main stone from, and a scrap dealer here offered me only $50 more for the setting with the diamonds in it than without. I took them and had studs made from them for $100 which would have sold for 3x that (which was probably what he was going to do).
Unless it is a collector’s piece, famous or rare, jewelry is a ****ty investment. Only buy what you love and will wear....anything else is a waste of money.