There are plenty of dealers that sell used, a.k.a. estate, a.k.a. second hand, a.k.a. resale, a.k.a. consignment, a.k.a. vintage, a.k.a. recycled diamonds. Some will trumpet this as a feature and others won’t mention it or might not even know. Prices on stones will vary quite a bit from store to store, just like with ‘new’ goods. Within the offerings of a particular dealer, there won’t be a significant difference in pricing for a particular stone based on the ownership history although there may be considerably differences between superficially similar stones for other reasons. Purchases from individuals are often priced lower than similar items from dealers but there are often other issues that make dealers worth considering.