Oftentimes mens rings like this have a hollow back. If it's not cleaned regularly, it will accumulate dead skin cells and bacteria which then can congeal into a solid mass. Back when I worked in jewelry repair, my coworkers and I called it "ring meatloaf".
As far as valuing the ring, I've seen similar styles sold at upwards of $4000. Those were solid 18k with nice quality diamonds though, so it's unlikely the Gunt's ring is worth nearly that much. Assuming it's not costume jewelry, I'd wager it's probably in the $1000-1500 price range. Wholesale price would maybe be $500.