Well, I guess it is like other online shopping. You'd really need to know what you were looking for, as far as cut, clarity, color. I'd also pay attention to the certification of the stones, if any, b/c some labs are more reliable than others. A good return period, w/ sufficient time to have the ring evaluated and I'd say no to a re-stock fee, esp. if it was not what it was alleged to be. Also, some ebay stores are actually stores in the diamond district in NYC- I'd check the id and google online and buy from the actual store/person, rather than on ebay first. The policies might be better and you can get more info.