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.

The price you're offered for your diamond can also vary hugely depending on how you choose to sell it. We've covered these reasons in more detail below. In most cases, a diamond engagement ring or other diamond jewelry will have a resale value of between 20 and 60% of the amount it cost when it was new.

Each piece of jewelry is thoroughly scrutinized for diamond quality, as well as overall manufacturing and craftsmanship. Costco's team of Gemologists, all of whom have graduated from a GIA program, inspect for diamond color, clarity, cut, and carat weight.

Because every designer is different, you will need to do thorough research on specific pricing for creating a custom diamond ring. The cheapest option that you have for a custom ring will be about $1000 and can climb all the way up to $40,000+.