Best Round Diamond for 7k – 10k, Deciding between Blue Nile, Costco, BGD and CBI Ideal Cut Diamonds

Hi Todd, I’m trying to find an engagement ring around the 7k – 10k range that is at least 1 ctw for the center stone. I have been looking all over the place and am a little worried about ordering from Blue Nile because I like to see what I’m buying before I actually buy it. I do want the best ring for the price and have been weighing the rings at Costco versus Blue Nile. I want the best ring for the money, but I’m not sure what I should focus on between color and clarity. I was wondering if you had any insight to help me on finding the best ring for the best price. Thanks! — Michelle

How to Judge Optical Symmetry in Round Diamonds:

Thank you for taking advantage of my free diamond concierge service Michelle, I’ll be happy to provide you with some options to consider. The first thing to be aware of regarding the diamonds offered by both Blue Nile and Costco is that both vendors represent a broad range of quality, in what is most likely an attempt to appeal to as large a segment of the population as possible… and very few people take the time to learn about the importance of diamond proportions, diamond cut quality, and optical symmetry when buying a diamond, because the majority of retailers compete on prices which are based upon the basic 4C’s of Diamond Grading:

  • Cut – which refers to Cut Quality and not Shape
  • Carat Weight
  • Color
  • Clarity

And people tend to assume that an overall cut grade of AGS Ideal-0 from the American Gem Society Laboratory (AGSL) or GIA Excellent from the Gemological Institute of America, means that the diamond has the best cut quality possible. However there is a wide variance in the optical symmetry of the diamonds which are to be found within the cut classifications of GIA Excellent and AGS Ideal.

How optical symmetry affects the visual performance of diamonds, Brian Gavin 104067973011For instance, you could select something like this 1.017 carat, H-color, SI-1 clarity, Brian Gavin Signature round diamond which exhibits a crisp and complete pattern of hearts and arrows, which is an indication that the diamond has been cut to a superior level of optical symmetry, because any variation in the facet structure of the diamond would result in visible imperfections in the hearts pattern. This diamond is graded by the American Gem Society Laboratory (AGSL) with an overall cut grade of AGS Ideal-0 which uses Angular Spectrum Evaluation Technology (ASET) to measure diamonds for brightness and light return, and looks great in all the reflector scope images!

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In addition to the insight provided by the ASET Scope, Ideal Scope, and Hearts and Arrows Scope images, I’m confident that this diamond will exhibit a high volume of light return and a virtual balance of brilliance (white sparkle) and dispersion (colored sparkle) because the proportions of the diamond are in the center or “sweet spot” of the range designated for the zero ideal cut rating. The crown angle of 34.8 degrees is a great offset for the 40.8 degree pavilion angle, and the 77% lower girdle halves are likely to create nice, broad flashes of light!

Or you could purchase this 1.04 carat, H-color, SI-1 clarity, round diamond from Blue Nile, which has an overall cut grade of GIA Excellent, but which we have no way to judge the degree of optical symmetry for because Blue Nile does not provide this depth of information. What I can tell you about the diamond is that the 34.5 degree crown angle is a great offset for the 40.8 degree pavilion angle, so the diamond should exhibit a high volume of light return with a virtual balance of brilliance and dispersion; but the 80% lower girdle halves will likely result in smaller flashes of light which are more like pin-fire… some people prefer this type of sparkle and other people prefer broader flashes of light, it’s just a matter of personal preference.

One of the things that I don’t like about buying diamonds like the 1.04 carat, H-color, SI-1 clarity, round diamond from Blue Nile is that there is no way to judge the degree of contrast exhibited by the diamond, because there isn’t a clarity photograph provided on the diamond details page… so we can’t judge the contrast of the arrows pattern that is created by the shadow of our heads reflecting off of the eight pavilion main facets located on the underside of the diamond, nor the extent that the tips of the arrows remain visible…

Blue Nile Signature round diamond reviews, GIA 2151798837Consider the variations in contrast that are visible within the arrows pattern exhibited by the 1.10 carat, H-color, SI-1 clarity, Blue Nile Signature round diamond pictured to the left. Look closely at the arrows pattern and you will notice that the shafts of the arrows are nice and black and exhibit a high degree of contrast, but the tips of the arrows fade out towards the edge of the diamond, and the arrowhead is practically non-existent in the arrow located in the relative two o’clock position. There is also a significant difference in the size and shape of the hearts, indicating a lesser degree of optical symmetry, including a difference in the length of the lower girdle facets.

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Needless to say that shopping for diamonds at Costco presents the same challenge in determining the degree of optical symmetry that the diamonds are cut to, because they don’t provide any of the reflector scope images required to judge optical symmetry.

What I can tell you is that when I ran a search for diamonds on their web site, I found nothing in the range of one carat diamonds, but I know that they do offer them in their physical locations… you could always purchase an ASET Scope, Ideal Scope, and Hearts and Arrows viewer and bring them with you into the store and try to judge the optical symmetry if the diamonds you are considering are unmounted.

Blue Nile Signature Round Diamond Review: GIA 216786099

Blue Nile Diamond Reviews, Signature Round Diamond, GIA 216786099Since you specifically asked about options from Blue Nile, I’ll continue to provide a few options from their inventory of Signature Diamonds that meet my selection criteria for proportions, inclusions, and overall cut grade with the understanding that there is very little that we can tell about the optical symmetry without images of the diamond as seen through an ASET Scope, Ideal Scope, and an Ideal Scope. This 1.01 carat, G-color, SI-1 clarity, Blue Nile Signature round diamond has a crown angle of 34.5 degrees which is offset by a pavilion angle of 40.8 degrees which is fantastic.

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As stated previously, this combination of crown and pavilion angle is well known for producing diamonds which exhibit a high volume of light return and a virtual balance of brilliance and dispersion. Once again the diamond has lower girdle halves which measure 80% and thus the diamond is likely to exhibit smaller flashes of pin-fire type sparkle. And as you can see by the clarity photograph provided above, the tips of the arrows are fading out pretty much all around the edge of the diamond, indicating a lesser degree of contrast… some people love this look and other people like to see more contrast and broader flashes of light, it’s all a matter of personal preference.

Blue Nile Signature Round Diamond Review: GIA 5166527451

Blue Nile Signature round diamond reviews, GIA 5166527451This 1.05 carat, H-color, VS-2 clarity, Blue Nile Signature round diamond exhibits better contrast which extends out to the tips of the arrows, but it is also apparent that the pavilion main facets are kind of thin, here again this is a matter of personal preference. This diamond has a crown angle of 35.0 degrees which is offset by a pavilion angle of 40.8 degrees with 80% lower girdle facets, you know what to expect by now – right?

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Blue Nile Signature Round Diamond Review: GIA 2135821748

Blue Nile Signature Round diamond reviews, GIA 2135821748This 1.08 carat, G-color, VS-2 clarity, Blue Nile Signature round also has a 35.0 degree crown angle which is offset by a 40.8 degree pavilion angle and 80% lower girdle halves, but do you see how the tips of the arrows fade out more than those on the 1.05 carat above? And how there is more variance in the size and shape of the hearts? This is why reflector scope images are such a critical factor of the diamond  selection process… there is simply too much variance in the facet structure of diamonds with an overall cut grade of GIA Excellent to make an informed choice without them.

Just look at how the entire left side of the heart is blacked out in the two o’clock position in the clarity photograph provided above… each half of a heart is created by the reflection of the pavilion main faceted located across from it, on the opposite side of the diamond, so it is apparent that there is some major deviation in the length of the lowr girdle halves of this GIA Excellent cut diamond.

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Suffice to say that there is a lot more to buying a diamond than simply restricting your search to diamonds with overall cut grades of GIA Excellent or AGS Ideal, but that is why I write articles such as this and offer a free diamond concierge service, in order to provide you with the information and insight necessary to make an informed decision, without having to become an expert on diamond cutting in order to choose the best round diamond for 7k – 10k.

This is the extent of the options which I found from Blue Nile which meet the initial phase of my selection criteria for proportions, overall cut grade, and inclusions… obviously they are cut better than the average round brilliant cut diamonds that you’re going to find in most jewelry stores, however there is a higher level of optical symmetry available from diamond cutters like Brian Gavin if you’re looking for something more precise which is apt to exhibit a higher volume of light return and better sparkle.

Brian Gavin Blue fluorescence diamonds reviews, AGSL 104069928006For instance, at the top end of your budget, there is this 1.242 carat, I-color, VS-2 clarity, Brian Gavin Signature round diamond which is cut like a dream and exhibits a beautiful pattern of hearts and arrows. And there is also this 1.295 carat, G-color, SI-1 clarity, Brian Gavin Blue (fluorescent) diamond which exhibits strong blue fluorescence when exposed to black light, as pictured to the left, but which will look perfectly normal in other lighting circumstances. These diamonds have an overall cut grade of AGS Ideal-0 and look phenomenal through the reflector scopes!

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Crafted by Infinity Diamond Reviews, AGSL 104058179003You might also want to check out the Crafted by Infinity diamonds which are represented in the United States by High Performance Diamonds, I find them to be comparable to Brian Gavin Signature diamonds in overall cut quality and visual performance. This 1.05 carat, G-color, SI-1 clarity, CBI diamondd has an overall cut grade of AGS Ideal-0 with proportions that are in the sweet spot, and it looks fantastic in all of the reflector scope images. You simply can’t go wrong with diamond cut like this, they truly represent the best that our industry has to offer and both BGD and HPD have great inspection and return policies so you can purchase from them with confidence. This 1.093 carat, H-color, SI-1 clarity, CBI and 1.097 carat, I-color, VS-2 clarity, CBI diamond also look promising!

Todd Gray
Todd Gray is a professional diamond buyer with 30+ years of trade experience. He loves to teach people how to buy diamonds that exhibit incredible light performance! In addition to writing for Nice Ice, Todd "ghost writes" blogs and educational content for other diamond sites. When Todd isn't chained to a desk, or consulting for the trade, he enjoys Freediving! (that's like scuba diving, but without air tanks)
Todd Gray

@NiceIceDiamonds

Professional diamond buyer with 30+ years trade experience in the niche of super ideal cut diamonds. In my free time, I enjoy freediving & photography.
The incredible #story behind the Sirisha diamond necklace by @BrianGavin 71 #Diamonds cut to order #Amazinghttps://t.co/dHOo1T99xT - 2 years ago

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2 comments
Michelle says March 17, 2014

Thanks for all of the info Todd! I really appreciate your help. Diamond shopping is very much trying to read through a foreign language. Your help was invaluable!

Michelle

Reply
    Todd Gray says March 17, 2014

    I’m glad that you found the article helpful Michelle! Let me know if I can be of further help… and by all means, send me a picture of the ring when you receive it!

    Reply
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