The 5 Cs: Buying a Diamond Ring at Costco, Part 1

February 1st, 2011 · 25 Comments

Cushion Cut Solitaire

Cushion Cut Solitaire

It’s that time of year when lots of people are thinking about getting engaged or looking for a special gift for their special someone.  And a lot of those thoughts, will require buying a diamond ring.  Costco is one place that not everyone would think of checking out in their pursuit of their diamond ring, but you really should consider it if you’re looking for high quality at a great value.  So, that’s my extra “C” in diamond buying: Cut, Carat, Clarity, Color, and Costco!

If you’re thinking about buying a diamond ring, you need to get very familiar with the standard 4 Cs of diamonds: cut, carat, clarity, and color.  It’s quite a bit of information to take in, but the more information you know before buying, the more satisfied you will be with your final purchase.  There are tons of places on the Internet where you can get more information than you will probably ever want about the 4 Cs of diamond buying, so I’ll try to just do a little brief introduction here (since I’m not anywhere near an expert).

The 4 Cs of Diamonds

Cut – The cut, not to be confused with the shape, is all about the facets in the stone.  A good or proper cut is what gives a diamond its brilliance, fire (technically, this is known as dispersion), and beauty.  It all has to do with how the light if reflected and refracted when passing through and bouncing back from the stone.  Elements of diamond beauty can be described as brilliance (all light returning to the eye), dispersion or ‘fire’ (seen as white light is broken into spectral colors), contrast patterns (contrasting light and dark areas created by the viewer’s reflection) and scintillation or ‘sparkle’ (seen as the diamond, the light source or the observer move). These qualities combine to create the life of the diamond and the way it reacts to lighting and environment.  The most popular diamond today is the Round Brilliant.  The important thing to know is that, if the cut is not optimized, the appearance of the diamond can be severely affected.  All of the diamonds at Costco are cut with a full 58 facets, except for some fancy cuts which may vary.

Carat – The weight or size of the diamond is measured in carats, abbreviated as ct..  A carat equals 1/5 of a gram and is sub-divided into points; one carat equals 100 points.  So a diamond weight of 1/2 a carat is equal to 25 points, likewise a 1.15 carat diamond is equal to 1 carat and 15 points.  Just because diamonds have the same weight does not mean that they will necessarily look the same size: depending on the cut a diamond may look bigger or smaller.  If a diamond is cut too deep or too shallow it may look small for its carat weight or have less brilliance.  Diamond prices rise quite a bit based on the carat weight: a 2-carat diamond of a given quality is always worth more than two 1-carat diamonds of the same quality.  To give you a little bit of help in determining how to judge carat weight and size, The Institute of Gemology (IGI) recommends the following vertical spreads for round brilliant diamonds.

At Costco, they list the minimum amount of diamond weight in each piece, though your diamond may actually be slightly larger, but never smaller, because they need to have multiple stones available in their inventory.  For instance, if you look online and decide to buy a ring that is listed as 1 carat, the actual stone you get on order fulfillment may be 1.05 carats (just picking a number at random).  When you receive your diamond you will also receive the appropriate IGI appraisal and/or GIA (Gemological Institute of America) certification. Jewelry items containing a 1.00 carat diamond or larger include an IGI appraisal. Jewelry items containing a 1.25 carat diamond or larger include a GIA Diamond Grading Report, in addition to the IGI appraisal. One-of-a-kind diamond items will include both an IGI appraisal and GIA Diamond Grading Report regardless of carat weight.

Clarity – Clarity has to do with the external and internal characteristics of the stone; these can affect how the stone can be cut and therefore its brilliance.  There are two types of physical characteristics that affect the clarity: inclusions, which are faults enclosed within the stone itself; and, blemishes, which are faults or marks on the outside of the stone.  Stones are graded using 10x magnification and the fewer inclusions or blemishes, the better the grade of diamond and thus the more it is worth.   The clarity gradings are: IF, VVS1 – VVS2, VS1 – VS2, SI1-SI2, and lastly I1, I2, and I3.  IF or Internally Flawless means there are no inclusions and only insignificant blemishes are visible under 10x magnification. VVS1 – VVS2 or Very Very Slightly Included means that there are minute inclusions that are very difficult to locate even at 10x magnification.  VS1 – VS2 or Very Slight Inclusions means that there are some minute inclusions that are difficult to somewhat easy to find under 10x magnification.  S1 – S2 or Slightly Included means that there are noticeable inclusions that are easy to spot under 10x magnification.  I1, I2, and I3 or Included means that there are inclusions that are easy to spot by a grader at 10x magnification and can be easily seen with the unaided eye.  Costco guarantees that all of their diamonds are of a VS2 (very slightly included) clarity or better.

Color – Diamonds can range from completely colorless to yellow or brown tint.  The most expensive diamonds fall in the colorless range graded D,E and F on a scale that descends to Z. If a diamonds has more color than Z, or in other shades such as orange, pink, blue, they are classified as “Fancy Colored Diamonds” and have a separate IGI grading scale.  To determine the color, all diamonds are compared to an internationally accepted master set of stones, the colors of which range from D, or colorless, to Z, with a visible yellow or brown tint (but not enough to be considered in the Fancy Colored Diamond category).  Colorless diamonds have a grade of D, E, or F; Near Colorless diamonds have a grade of G, H, I, J; Slightly Tinted diamonds are graded as K, L, M; Very Light Yellow diamonds are N, O, P, Q, R; and, Light Yellow diamonds are S, T, U, V, W, X, Y, Z.  Since there are many factors that can affect the color grade such as lighting, mounting choice and even the clothes one wears, IGI uses the most neutral environment possible to ensure accurate and consistent results.   The bottom of Costco’s color scale is actually I to ensure that their diamonds have a very near to colorless appearance and do not have a chance of having a slight tint.  They feel that the I grade offers the best quality to value, and therefore price for their customers.

Shape – Even though, it isn’t in the 4 Cs of buying a diamond, the shape is definitely something you probably want to think about before making your purchase.  There are nine shapes for diamonds, and all of them have their own beauty and can have varying amounts of sparkle.  Really, I think the shape is pretty much down to personal opinion.

Diamond Shapes from the GIA

Diamond Shapes from the GIA

I suggest that you learn all you can about buying a diamond, before you begin shopping, and luckily there are plenty of online resources to help you out.  I would suggest reading the information provided by the International Gemological Institute regarding the 4 Cs, shape, as well as the importance of an IGI certification.  They also have a useful section on how to care for your diamonds or other jewelry once you’ve made a purchase. also offers some useful diamond buying information.  They have a helpful F.A.Q. about Costco diamonds (PDF) and jewelry. also offers a diamond education PDF that covers the 4Cs of diamonds, though the quality is a bit dodgy.

So, why should you buy your diamond ring at Costco?'s 5.11 ct solitaire for $193,999.99's 5.11 ct solitaire for $193,999.99

Costco is very committed to quality in their diamond jewelry, just like in all things they sell. This goes to the level of them having their own lab and team of graduate gemologists at their diamond distribution center.  This helps them to verify that all of the stones that they receive  meet their requirement of being at least a VS2 clarity and I color grade.  They also inspect the stones to make sure that they do not chips.  Costco will also not accept synthetic diamonds, or natural diamonds that have had their imperfections microscopically filled or laser treated.  They will also not accept diamonds that are pressure or heat enhanced to artificially bring out the color.  So, all of that amounts to Costco really looking out for its customers because they want to make sure that when you buy a diamond from them you are getting the quality that you expect.

Costco’s gemologists inspect every single diamond, no matter what carat size.  They do this to make sure that  all diamonds meet their standards, as well as to authenticate all supplier reports.  All diamonds that pass the team’s inspection receive a Costco report that contains a photo and appraisal.  The gemologist team actually rejects about 7 per cent of the diamonds they receive from suppliers.

Also, Costco does not buy conflict diamonds and checks to make sure that their diamonds are obtained through legal channels set out by the United Nations Kimberley Process.   This process requires manufacturers to comply with a procedure that closely tracks, ships and received each diamond, with documentation for each set to monitor the stones’ origins.

While the selection at Costco might not be enormous, or as wide ranging as other retail jewelry stores, you can be sure that they actually are the quality that you think you are buying.  You can’t change the settings or the size of the diamond either when purchasing through Costco, which might be a problem for some people.  The selection available at the warehouses varies by location, and is also smaller than what you can find at   Currently, they have a very wide selection of diamond solitaires online, as well as a pretty good selection for engagement rings.

There are many different kinds of diamond and gem stone rings, earrings, bracelets, and necklaces available at  The type of ring you can purchase just depends on what you want to spend and what your personal tastes are as far as jewelry goes.  For the classic solitaire you can choose from the nine different shapes (see the image earlier in the article).  You can also choose from different metals for settings: platinum, white gold, and yellow gold.   Since solitaires are all about the stone, really, it is nice to have such a wide variety of options as far as shapes, clarity, color, and setting go.  Costco even has a very easy to use way to select your unique diamond solitaire that will allow you to choose the diamond shapes you prefer, as well as ranges for price, clarity, color, and carat that suit your needs and budget.  I highly recommend this for anyone looking for a diamond solitaire.

If you’re looking for something even more spectacular, you can order a one-of-a-kind diamond through Costco too.  If you are interested in going this route, you can either shop the selection online or call the help line at 877.864.8695 or email them at  You can check out some of the current one-of-a-kind rings on offer at right now.  They are all fairly spectacular and have some spectacular prices to match in a lot of cases; prices range from $4,000.00 all the way up to $194,000.00.

The other good thing, possibly the best thing, about buying a diamond through Costco is that they still have the same excellent return policy.  If you buy a diamond at Costco as a gift and the person doesn’t like it, for whatever reason, you can return it to Costco for a full cash refund.

I really want to do a price comparison between and other online jewelry retailers.  However, this post is already getting kind of long (okay, very very long), so I’m going to do a follow up post on Thursday where I carry out a comparison between,, and (those three for sure).


Tags: · gifts · jewelry Share

25 Responses so far ↓

  1. 1 Miranda // 2016.12.07 at 9:10 pm

    I have never set foot at any Costco store but there is one opening soon in Wesley Chapel, FL….. the first thing I will check out will be their jewelry case for an anniversary ring (our 25th)…… can’t wait….. Miranda

  2. 2 Kakadiya Group // 2016.09.12 at 1:49 am

    Sharing such a nice content…!

  3. 3 Jennifer // 2016.03.11 at 12:41 pm

    This article and all the comments were extremely useful to me, so I thought I would share my experience. When my fiancee sent me pictures of a diamond wedding set (engagement ring and matching wedding band) that he liked from the Kirkland, WA flagship store, I was cautiously optimistic. After all, we were big Costco fans, they have an excellent reputation in the community, and we know a local jeweler who we trust to help us decide and for service afterwards. It was a white gold set with 1.5 carat total weight. 4 princess cut diamonds on the engagement ring, plus 18 brilliant cut. 20 brilliant cut diamonds on the wedding band. We did a lot of research online and in jewelry stores. I couldn’t find another ring I loved more in terms of style and sparkle, so we made the purchase. Between our jeweler friend and Costco’s return policy, we knew we could return the set if we were not satisfied. Because none of the individual diamonds were greater than 1 carat, we did not receive a GIA cert, but did get a summation of appraisal document. Our jeweler checked the rings out for us and did an appraisal. He was VERY impressed! The diamonds were VS1 and I as advertised. They were well cut and had major sparkle. He appraised the set at $1700 more than we paid, and shook his head at how Costco could afford to sell jewelry at their prices. Because the rings came only in a size 7, I was lucky that I am a size 6.5. Our jeweler did the re-sizing. We paid only $30 per ring for the appraisals, and $60 per ring for the re-sizing. I would agree that Costco may not be the best choice for a jewelry purchase of this importance if you need education or service. However, if you have a local reputable jeweler to help you, and you are educated on diamond purchases, you get a lot of bang for you buck! No one has ever asked me where my rings were from, and I wouldn’t be ashamed in any case. We are thrilled with our purchase.

    • 4 Jeff // 2016.10.22 at 4:24 pm

      Jennifer, I am looking to purchase the same diamond wedding set as you described from Are you still satisfied with this ring or have you had any issues with stones falling out etc?

      • 5 Jennifer // 2016.10.22 at 4:44 pm

        Hi Jeff, It’s been 7 months since we purchased the rings, and I am more in love with them than ever! Zero quality issues. Just as sparkly and brilliant as ever. I often get compliments on my engagement ring. We couldn’t be happier.

        • 6 Jeff // 2016.10.22 at 6:14 pm

          Thank you so much for that. I did receive it this week and haven’t given my to my wife yet (after 23 years of marriage I’ve decided to surprise her with an updated ring). I took the ring to a trusted jewelry store and he appraised yesterday it for $2400 more than I paid and gave it a H color instead of I, but gave it a one level worse on the clarity. I do understand they inflate the appraised value typically though. My only fear was whether the four small princess cut diamonds in the setting would come loose since the appraiser noted he wouldn’t clean it if I brought it to him due to the risk that one of those diamonds comes out. He said they should be held by little ‘L’ brackets versus the four little prongs holding it. He said as soon as my wife puts lotion on her hand he would be worried that something could go wrong or lotion would come through the four diamonds and something could get loose. I’m guessing you don’t have those problems or any issues with loose stones. She isn’t extremely active with her hands so I wasn’t too concerned. Thx again for your thoughts on this ring as I was debating this one and another one at Costco which is $600 off this week but about $700 more than the one you have. Thanks! ….Jeff

  4. 7 Buying Engagement Rings From Costco | My Engagement Ring // 2014.11.29 at 6:10 am

    […] The 5 Cs: Buying a Diamond Ring at Costco, Part 1 … – Feb 01, 2011 · The 5 Cs: Buying a Diamond Ring at Costco, Part 1… […]

  5. 8 Heather // 2014.11.26 at 2:33 am

    Worst service ever. I used to LOVE Costco. Tried to buy an $11,500 diamond engagement ring and order was cancelled twice without notification. Even after verifying charge with my credit card. Unbelievably disappointed and an emotional nightmare. Spent an HOUR on the phone redoing the order and it was cancelled again. I give up. What a waste of time and energy!

    • 9 vicki // 2014.12.27 at 7:29 pm

      Do you know where Costco gets !heir jewelry from.

  6. 10 Todd // 2014.04.21 at 11:59 pm

    I have seen amazing engagement rings at Costco with high quality specs. However, I am unclear about the Cut. They say it’s round brilliant and neglect to mention the grade of it (ex. being ideal to poor). Any thoughts?

  7. 11 Gayle // 2014.01.06 at 1:27 pm

    We purchased my princess cut with two trillion cut side diamonds wedding ring at Costco. I immediately had it appraised at a gemologist for insurance purposes. The ring appraised out $7000.00 more than we paid for it! Costco also guarantees their rings and stones.

    I would highly recommend purchasing a wedding ring from Costco. I did not like the high pressure sales tactics at name brand stores. We looked there and I just felt like I was getting ripped off…the same creepy feeling when you buy a car sometimes.

    I could care less that it was purchased at Costco. I love the ring! If you are planning on getting married and your future wife cares about the name on the box or the receipt – then maybe you need to think. Costco is a tremendous value on diamonds.

    You are starting a life together – why start it getting ripped off at a name brand jewelry store?

  8. 12 Sharon // 2012.04.07 at 4:21 pm

    How can the average person be sure they’re getting the most quality/value for their money when purchasing a gemstone and diamond ring?

    • 13 Christine // 2012.08.26 at 4:06 pm

      The diamonds sold at Costco are high quality–you are getting the best there. And at a good price. Jewelry stores
      sell commercial diamonds–don’t’ waste your time or money. Sometimes you can find good deals on Craig s List–but always
      do the deal at your jewelers who can verify the quality of the diamond.

  9. 14 Neil // 2011.04.21 at 6:24 pm


    Check out the Kirkland and Issaquah stores for the best selection of high-end diamond jewelry in the case. Kirkland is their flagship store, and also an affluent area, and has plenty in the high-end case ranging from 10K – 50K USD.

    The Issaquah store will have a different selection, and as it is across the street from Costco’s corporate headquarters, they often try out new inventory or uncommon products in that store, as the corporate people like to come by and see how in-store operations are going on a daily basis. A friend saw Jim Sinegal in the store this last weekend.

  10. 15 Heather // 2011.04.21 at 1:03 pm


    I am a Canadian and our diamond rings are not as nice as the ones that you guys have! I have found many on the website, but again, Canadians do not have access these products.
    We are heading down to the Seattle/Kirkland area next weekend. I know it is a long shot, but does anyone know what rings they have in stock now? We are looking for a min 1 carat solitaire with halo and diamonds on the band. Thanks!

  11. 16 Ed // 2011.02.27 at 7:39 pm

    Well, this is an update to my ordeal with the ring I purchased… I called their main Costco office and found that after explaining the journey this project turned into… I am satisfied with the level of commitment they had in trying to make things right. Their jewelry department shipped 4 additional rings to my local Costco for me to inspect. They made it clear that they would try their best as these rings where hand made.

    Thank you Costco for standing by your products and making sure that your members get a good service and product after all! …. Just please… try to inspect items more carefully, specially when labeled “Hand Made”…. “Hand Made” should not mean crooked or slapped together… but it should be of higher quality if anything. I don’t know of any diamond jewelry that is not hand made… I guess after all this running around and hand selecting this ring, now its worth more!…Hahaha…. but really there is nothing to joke about… I did go WAY out of my way to make sure Costco was aware of the poor craftsmanship I encountered time after time with this item! I guess I had a little spare time… But for now, for your customer’s sake, ya might wanna think about making a quality product that has been carefully inspected to began with!

    BTW… there is no comparison to Costco’s return policy so I will buy my wedding bands there two… even after all of this… I can’t think of a better place I can get the best bang for my buck!…

    • 17 Kimberly // 2011.03.03 at 2:34 am

      @Ed – Hey, glad to hear that things worked out. But sad that it took so much of your time. Hopefully, Costco’s diamond lab will learn from this and be more careful with their inspections.

  12. 18 Ed // 2011.02.25 at 3:46 am

    Just purchased a diamond engagement ring at Costco and after careful inspection I noticed the center diamond was set crooked. I was surprised as I buy lots of stuff at Costco. Just want to share my story after driving a little more than 400 miles between 4 Costco warehouses who where the only ones that carried that style ring! Its just upsetting to find that out of 7 engagement rings all had their center or side stones crooked! Poor craftsmanship of finished product at 100%! Don’t get me wrong though, I buy lots of stuff there including a previous (promise) ring so I figured I would return to Costco for a second ring since I’m getting married soon. It’s just too silly of professional people working there such as the buyer to not be aware that who ever the supplier is of this ring “is doing such a crappy job with the setting of the diamonds”. Gemologist grade the diamonds but a jeweler sets them! The diamonds are good but the CRAFTSMANSHIP SUCKS! FYI…Take your own loupe (cost like $20 for a 10x and worth the money if you are spending $$$ on a ring) as you will need it since corporate doesn’t make it mandatory for Costco warehouses to have them! Go figure why all places selling diamond jewelry have them and some Costco don’t! What upsets me the most is the waste of my time driving around because we all know, not all Costco warehouses sell the same things… Outcome = UPSET and completely Dissatisfied with the Craftsmanship!
    What a waste of my time, gas and money!

  13. 19 The 5 Cs: Buying a Diamond Ring at Costco, Part 2 | Addicted To Costco! // 2011.02.05 at 5:08 am

    […] policy archives guest posts costco locations costco coupons about home ← The 5 Cs: Buying a Diamond Ring at Costco, Part 1 This Week at Costco – January 30, 2011 […]

  14. 20 Emily (Bentobloggy) // 2011.02.01 at 10:35 pm

    I have to say, the first place I stop when I visit Costco each and every time is the jewelry cases. I’m a big jewelry addict, but so far I’ve never purchased any fine jewelry from Costco, probably because I have my jeweler make me antique reproduction pieces or buy estate items, but recently I’ve seen some very, very nice vintage and antique-styles at Costco, following in that current trend. Great post, Kimberly!

  15. 21 Emily // 2011.02.01 at 1:55 pm

    I love my Costco diamond ring, my husband couldn’t have done any better!

  16. 22 Mike // 2011.02.01 at 11:59 am

    Thanks for doing this series of posts.

    Someday I am going to buy my wife a nicer ring and we were definitely thinking about Costco.

  17. 23 Kimberly // 2011.02.01 at 11:19 am

    Thanks, tle. Well, the fact that you can take it back for a full refund is a little bit of reassurance for buying online. But definitely if you live near an area with a Jewelry District (like Chicago or New York), you really should check them out. Such a great selection in places like that. Plus, as you said, you have much more flexibility with the setting because you buy the diamond separate from the setting.

  18. 24 tle // 2011.02.01 at 9:49 am

    Nice post. You can also go to the Jewelry District (if you are in the LA are) and compare prices. I got my wife’s engagement ring, 1.5 carat, color F, VS2, round tradition cut… for $13,000. I would have bought it from Costco if I could hold it and look at it, plus at the store, I can chose the ring setting and they set the stone in for you. I did and still buy other jewelry from Costco, sight unseen and I am pleased with the quality and price.

  19. 25 Tweets that mention The 5 Cs: Buying a Diamond Ring at Costco, Part 1 | Addicted To Costco! -- // 2011.02.01 at 7:08 am

    […] This post was mentioned on Twitter by Kurt, Amber Henry. Amber Henry said: The 5 Cs: Buying a Diamond Ring at Costco, Part 1 | Addicted To …: When you receive your diamond you will also… […]

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