Diamond Pro is reader-supported. When you buy through links on our site, we may earn an affiliate commission. Learn More.

Deal Alert! 25% off at James Allen and 15% off at Blue Nile!

Please enter your email address to receive your personal one-time use unique coupon code - $100 off $1000:

Costco Diamonds & Jewelry Review: Good or Bad Deals?

Overall Score:2.17
2 Rating
Price:3.53.5 Rating Selection:11 Rating Customer Service:22 Rating
  • Great return policy

  • Non-existent service
  • Poor selection
  • Mediocre pricing
Other Recommended Retailers

Bottom Line

In the past, when Costco sold their diamonds with GIA (Gemological Institute of America) certificates, they had legitimately very good prices. Now that they have relaxed their standards (yet still charge the same price), their value has dropped significantly.

Costco has fundamental drawbacks inherent to their business model. They have no service in the store and their selection is very poor. Contrast their selection with the thousands of possibilities you can see at a jeweler. Take James Allen’s inspiration gallery, where you can look at endless diamond and ring setting combinations, for example.

As you will read below, the prices aren’t too hot either. Here is a stunning 3/4ct diamond and beautiful ring that cost almost 30% cheaper than the ring we found at Costco. 

With their drop in quality/value paired with their lack of service and selection, you should not be buying diamond engagement rings from Costco. You will be much better off buying your diamond from a top online dealer like James Allen or Blue Nile. If you prefer some personal help in finding the right ring, feel free to contact us.

Background of Costco Jewelry

There is no reason for me to bother with a history of Costco — the company’s reputation precedes them. Speaking personally, I love Costco. My family and I have been long time customers of Costco and I admire the company’s philosophies.

Costco Wholesale Corporation has built a fantastic business model of providing bulk items with razor thin margins. For a major retail chain, their service is second to none. They also have a legendary return policy.

Costco used to have a great reputation for jewelry as well. Speaking from experience, from the perspective of a supplier, I used to be impressed with their quality control. Unfortunately, the quality of their jewelry has seemed to have slipped over the last few years.

When I started with this site, I would get emails from readers asking about Costco diamonds. They used to have diamonds with GIA certification. As you will see below, this is no longer the case.

The Costco Engagement Ring Shopping Experience

Costco is a phenomenal retailer, but they are a terrible jewelry store. There are no knowledgeable staff members and no value added services. You pick out the diamond the same way you pick out a shampoo bottle or one of their delicious cheesecakes. I went with a 0.70ct I VS2 round in a solitaire setting.

We always recommend that our readers contact us for specific advice when buying a diamond from a local jeweler. If you were to contact us after looking at a diamond ring at Costco, you will invariably get better, more thorough advice from us and whichever online retailer we recommend. That should be the one area a brick and mortar retailer should excel in, not fall behind.

Costco Appraisal - Click to Enlarge

Costco Appraisal – Click to Enlarge

This is where you start to see cracks in the Costco experience. Not only was the diamond lacking a GIA certificate, it didn’t have any certificate at all.

To their credit, this was a well cut diamond (I can’t give specifics as it was mounted already) and the clarity grade was fair. However, the diamond was a J color, not the I color they claimed it to be. Learn more about cut, color, and clarity in our useful guide on the 4cs.

The actual setting, while simple, was fantastic. It was a classic four pronged platinum solitaire. The craftsmanship and quality was on par with any company that I would entrust. Overall, the ring I purchased was a nice choice, right in line with our recommendations (an eye-clean, well cut J color for a solitaire).

    Ringo Approved Eye Clean Diamonds

  • Blue Nile

    Carat Weight 0.70

    Color J

    Clarity SI2

    Check Price
  • Blue Nile

    Carat Weight 0.70

    Color J

    Clarity SI1

    Check Price
  • Blue Nile

    Carat Weight 0.60

    Color J

    Clarity SI2

    Check Price
Load More

Costco Ring Setting and Style Selection

Another issue that crops up is their lack of selection. At any given store, they will only have 10-20 options. The quality and craftsmanship is fantastic, but that leaves little room for individuality and personal tastes. Even if you look online, their options are limited. They only have about 7 different solitaire setting options for round diamonds. To contrast, James Allen has about 50 settings covering a vast array of ring styles and Blue Nile has an eye-popping 66 different solitaire selections. The ring we bought was a perfect example. While it was very nice, my friend (who joined me for the secret shopping and tried on the rings) was not overwhelmed by the style. Afterwards, we were looking online and she was immediately drawn to a more delicate style like this 1.5mm comfort fit setting.

Costco Diamond Price and Value Comparison

Though the ring is nice, the value is just not there. The ring cost $3,503.99, including tax. Any way you cut it, the price is not justified by the product. Two comparisons can be made here, one based on my grading (J VS2) and one based on their grading (I VS2).

The Ring from Costco - Click to Enlarge

The Ring from Costco – Click to Enlarge

Here we have a beautiful 0.70ct J VS1 to go along with this platinum solitaire setting from James Allen. This is a virtually identical ring, retailing for $2,740, a whopping 25% cheaper with sales tax included. Please don’t take our comparisons here as recommendations for what you should buy (though that is a great looking diamond). We are just trying to find similar diamonds so we compare apples to apples. If you are looking for help buying an engagement, contact us and we will make personal recommendations for you.

Even if you want to go with their grading (despite them no longer using GIA certification), you would still save 28% if you went with this 0.70ct I color VS2 Clarity Excellent cut from Blue Nile and paired it with this solitaire setting.

Those savings, while significant, are not as dramatic when comparing other brick and mortar retailers to online retailers. Given Costco’s lack of diamond service, however, I think that drop is very significant.

You don’t have service for sizing, any sort of warranty, and there is a very limited selection of setting/diamond options. While you can do some research and due diligence on your own, there is no personal service at Costco.

Costco Diamonds Review Conclusion

You won’t be disappointed with the quality of your purchase. However, Costco is nowhere near close to offering the best price for quality diamonds.

If you are buying an engagement ring or stud earrings, you can get far better value and service using a legitimate online retailer. Additionally, you should never buy a diamond without a legitimate certificate (like GIA or AGS).

For items that don’t require certification, such as diamond jewelry or wedding bands, they could be a worthwhile option. I would recommend contacting us and we’ll find you the best option regardless what you are looking for.

Think You’re A Diamond Pro?

These diamonds look identical in a ring.
Real Diamond Pros will know how to save almost 25%
So Which is it?
The J color at $4040
or the G color at $5406
Choose the diamond you like better and see if you are a Pro!

About the author
Michael Fried
Mike learned the diamond business from the ground-up at Leo Schachter Diamonds - one of the world's top diamond manufacturers. He has been recognized as a diamond industry expert by Time, PeopleMoney, The Daily Mirror, NerdWallet, The Times Herald, Yahoo Finance Australia, The Art of Charm, The Washington Diplomat, The Next Web, and more.
Top Recommended Vendors
Blue Nile Blue NileBlue Nile is the largest and most well known internet jewelry seller. They have a very large exclusive online inventory. Their high quality images are catching up to James Allens' and their prices are amazing. Blue Nile is currently running a limited time sale offering 15% on settings site-wide. Click here to browse some great settings.
What we love about them:
  • No questions asked returns within 30 days of shipment. Blue Nile will send you a paid shipping label to return the ring.
  • Lifetime Warranty
  • Free Shipping
  • Free prong tightening, repolishing, rhodium plating and cleaning every 6 months
  • Provide insurance appraisal
  • One free resizing within the first year of purchase
  • High quality images of about half of their diamonds
  • 24/7 Customer Service
  • 100% credit towards future upgrades (must be at least double in value)
  • Best in class fulfillment
Arrow down
Arrow up

James Allen James AllenJames Allen is the leader in online diamond sales. Their imaging technology is the same as inspecting a diamond with a jeweler's loupe. They have the largest exclusive loose diamond inventory online and fantastic prices. They also have the nicest collection of lab created diamonds online.
What we love about them:
  • No questions asked returns within 30 days of shipment. James Allen will send you a paid shipping label to return the ring.
  • Lifetime Warranty
  • Free International Shipping
  • Free prong tightening, repolishing, rhodium plating and cleaning every 6 months
  • Provide insurance appraisals
  • One free resizing within 60 days of purchase
  • Free ring inscriptions
  • Best-in-class high quality imagery of all diamonds in stock
  • 24/7 Customer Service
  • Best-in-class packaging
Arrow down
Arrow up

Still afraid of getting ripped off?

Before you buy a diamond, get personal buying advice from industry veterans. We'll help you get the best diamond for the money.

Ask your diamond purchase question here

  • Hidden
  • This field is for validation purposes and should be left unchanged.

DISCLAIMER: We don't use your email for marketing. Period.

Ask your diamond purchase question here

We are a team of diamond experts who will teach you to identify scams and avoid spending money on features you can't see. Tell us as much information as possible to help us help you (ie, budget, preferences, etc)

  • Hidden
  • This field is for validation purposes and should be left unchanged.


DISCLAIMER: We don't use your email for marketing. Period.

Please enter your email address to receive your personal one-time use unique coupon code - $100 off $1000:

Here is your coupon code: GFDSF3GF