In the US, if you buy stolen merchandise and did not pay a fair market price, you can be charged with buying stolen merchandise. And that can be a dangerous because of differing perceptions on what an item is worth. Jewelry is a good example. The standard for the industry is triple cost for new jewelry. You can buy it used for the scrap value which is actually less than cost. A 14K ring is only 58.5% gold. The rest is alloys. Any diamonds, in the ring, do not have a scrap value but is still less that retail.