I'm not sure but I do remember reading something about the high quality of Costco diamonds.

Here's a link to an article about Tiffany and Costco - it's mostly about a dispute between Tiffany & Co. and Costco, but midway down there is information comparing diamonds from both places.

http://www.businessweek.com/articles/2013-05-06/tiffany-vs-dot-costco-which-diamond-ring-is-better

Are you interested in diamond studs or earrings with lots of smaller diamonds? If you're looking at diamond studs then it's easier to ascertain the value. Unless they're really small you should get an appraisal. I tried Macy's web site, filtered for the most expensive studs and they did list the 4 C's. I can't speak for the accuracy since it didn't mention if the appraisal was G.I.A. or just Macy's description.

If you're interested in earrings with lots of smaller diamonds then you'll probably only get a t.c.w. description, without any grading.

We buy most of our jewelry from a local jeweler who we have dealt with for nearly 30 years. We've bought new jewelry, estate items and he's made several custom pieces made for us. DH is very knowledgeable and often buys loose stones from him and then the 3 of us design the setting. He believes that we receive a better price and certainly better service from our local jeweler. Our jeweler is an independent business but he travels to Tucson every year for the gem show which is the largest gem and mineral show in the U. S.

Costco has a fairly good reputation for their jewelry. The more expensive ones have G.I.A. appraisals. Tiffany recently filed a trademark infringement against Costco for selling Tiffany rings, which obviously weren't from Tiffany. I've looked at their jewelry and they do have some really nice pieces. I wonder how many brides have Costco engagement rings.

It wouldn't matter if they all bought their pieces from the same place. There is such a vast range of quality that I don't think you could base your decision on that. It's more important to trust that you're dealing with a reputable business.

Maire

Costco is a great place to buy quality diamonds. Make sure you see the certification. Larger diamonds cost more because there are less of them. Then you must consider the quality and the cost and rarity skyrockets.