The prices can be just half the cost of a similar ring at a big-box jewelry store. Compared to online jewelers, here's the general observation: Diamonds 1 carat and above have similar pricing, since the diamonds are certified by GIA. Diamonds under 1 carat are cheaper at Costco, since they're not certified.

Costco offers our members high quality jewelry at an exceptional value. Our team of GIA Graduate Gemologists inspect every diamond to ensure it meets Costco's strict quality standards. We only sell natural and untreated diamonds.

Antique cuts actually tend to be less expensive than modern cut earth-mined diamonds if and when you can find them. Part of this reason is because they don't require new mining and all of the associated costs that come with that.

Andy Johnson - Owner - diamond cellar holdings | LinkedIn.