Selling jewelry can definitely be a profitable business. I have personally made some good money from reselling pieces online. Pro tip- Always check pockets and inside of purses! I found an amazing gold cocktail ring with dozens of tiny diamonds inside of a vintage purse. Since I was paying for the purse, I essentially got the ring for free. Instead of selling it, I decided to hold onto it as a gift to myself. I’m not the only one who has been so lucky. A woman who found a diamond ring at a garage sale for $13 was able to sell it at Sotheby’s for $850,000.
The tricky part is learning the skills to identify the jewelry, or be willing to pay for appraisal. A thrift store near me was constantly getting donations of costume jewelry, and occasionally got lucky finding real gold. So they decided to try to expand the business by buying jewelry for resale. However, they weren’t professional jewelers. Even though they bought a gold testing kit, they made a lot of mistakes. Eventually, they were losing money, and had to give up that part of the business completely.