Look at the beautiful blue topaz to the right.  It is set in 14Kt gold and is trimmed with diamonds and another set of blue topaz on the sides, very unusual and very beautiful.  Finding a buyer for it is tricky.  eBay is full of blue topaz sellers, some selling blue topaz at $10 for a gemstone this size.  Cruise ships are nortorious for selling look blue topaz at cheap prices because they look so beautiful and can be bought at such good prices.  The expensive part is setting them in a mounting.  The gold mounting pictured here cost the jeweler nearly $300, so along with the small price paid for the topaz, the ring sold for around $600 retail.  That's a fair price, but the "value" to a second hand store or a scrap merchant is minimal.  You should expect to get around $100-$125 for this ring, simply because there isn't a good secondary market for used colored gemstone jewelry.  I will put the ring on eBay myself, but I only expect to get around $195 for the ring.  After my selling expenses for polishing the ring, PayPal and eBay, I will net around $50 profit.  That's not a lot of profit for such a nice ring, but that's the market.