Selecting the Best Option on Blue Nile Diamonds

Greg writes: “Hi, I really like your website and appreciate the detail you have with pictures – most sites rely on the same generic charts. Over the past month or so I’ve researched diamonds non-stop. I’ve made complex spreadsheets to determine the best value. My diamond value calc is really accurate to what people I know have bought and ended up with. I made this after a jeweler told me I couldn’t spreadsheet diamonds and was trying to sell me stones that were too great in one area and too poor in another instead of a well-balanced stone.”

[Client inquiry continued] “That said, I’ve narrowed my search to a diamond as close to 1.49 carat as possible, with G color, VS1/VS2 clarity, and excellent in the other aspects, no fluorescence, and as close to ideal in proportions as possible. The jewelers I’ve been to were charging 20%+ more than what I found online for the same stones. In a lot of cases I wasn’t shown stones that nice because they were out of the price range I told them. Anyway, with that specific diamond in mind I’ve searched Blue Nile, and a few equivalents. Blue Nile is great because I can view the certificates. But upon doing so I noticed the varying inclusion types and placements in the diamonds. Your site was helpful in informing me more about these but filled me with a bit more doubt on buying online. The stones I’ve been looking at with the grades above are anywhere from 12k to 14.5k. So, my questions are; How, if at all possible, to choose which stone from the small list of finalists on Blue Nile? How come some VS2 stones seem to have less/better inclusions than some VS1 stones I’ve seen? And, Is there anyway to pay Blue Nile prices, get the stone I want, but do it in person living in San Diego? Please help! Thanks again and excuse any misspellings or grammar as I’m typing in this very small box, ha ha.”

Your experience with shopping for a diamond within the traditional brick and mortar jewelry store environment is pretty common Greg, it seems like the majority of jewelry stores try to ignore the technical details and hope that their customers do not research the details of their purchase online.

The business model of Blue Nile revolves around having exclusive access to the largest inventory of virtual diamonds available online; however because Blue Nile does not have the majority of diamonds which they offer in their physical possession, they are not able to provide the additional details which other online vendors such as Brian Gavin Diamonds, High Performance Diamonds and James Allen make readily available… such as detailed clarity photographs, a computerized proportions analysis of the diamond, and images of the diamond as seen through an ASET Scope, an Ideal Scope and a Hearts and Arrows viewer.

Like the majority of traditional brick and mortar jewelry stores, Blue Nile relies on the information provided on the diamond grading report to provide consumers with a description of the characteristics for each diamond that they offer.  Thus Blue Nile primarily competes with traditional brick and mortar jewelry stores on the platform of availability and price.  Seemingly savvy diamond consumers can compare the characteristics stated on the lab reports and make an informed decision… however there is a lot of pertinent information which I feel is critical to making an “informed decision” which is not provided on the diamond grading reports issued by the various gemological laboratories.

Specifically the in-depth nature of the diamond cut quality and the degree of Azamet Shift and since these two factors contribute to the sparkle factor and visual performance of the diamond, I consider them to be critical factors to the diamond selection process.  It is important to note that the lack of this information should not preclude you from buying I diamond from Blue Nile, it just means that consumers need to be proactive about requesting more detailed information from Blue Nile prior to purchasing their diamond and/or consult with a qualified independent Graduate Gemologist to have the diamond evaluated in a more detailed fashion prior to completing their purchase.

In your particular instance Greg, I would recommend that you arrange to have whatever diamond you purchase from Blue Nile be evaluated by Thom Underwood of San Diego Gem Lab because he can provide you with a more in-depth analysis of the diamond.  Now Thom does not have the ability to provide you with computerized proportions analysis of the diamond using a Sarin, OGI or Helium machine; however many of the diamond cutters which Blue Nile is associated with do have these devices on the premises and can provide the reports upon request… be sure to ask for the detailed analysis which provides the high and low measurements for the crown and pavilion angle and if possible the facet-by-facet breakdown for these sections because it will provide you with amazing insight into the diamond cut quality.

The reason why this information is critical to the process of selecting a round brilliant ideal cut diamond is because the measurements stated on the diamond grading reports for the crown angle and pavilion angle are the average measurements for each section based upon eight individual measurements.  Without knowing what the range is for the high and low measurements, there is no way to determine how tight the diamond is actually cut because a crown angle of 34.5 degrees might be the result of a high of 34.7 degrees and a low of 34.3 degrees which would be exceptional, or it could be the result of a high of 35.5 degrees and a low of 33.5 degrees which would indicate that the diamond is sloppily cut and will exhibit a lesser degree of light return in spite of seeming to have the right proportions as indicated by the measurements provided on the diamond grading report.  It is also important to take into account the flow of how the facets per section of the diamond increase and decrease in terms of the measurements, it is one thing for the measurements to gradually increase in one direction and quite another if the measurements are jumping up and down from one facet to the next in terms of how the light will move through the diamond and be reflected back up through the top of the diamond.

The next factor which is critical in selecting a diamond is determining the degree of Azamet shift exhibited by the diamond and the only way to make this determination is to examine the diamond using a Hearts and Arrows scope.  Azamet Shift is the subtle shifting of facet alignment which occurs during the diamond cutting process as the diamond cutter makes minor adjustments to each section of the diamond as it is cut… many round brilliant cut diamonds which are mass produced using automated diamond cutting machinery exhibit dramatic Azamet Shift because the diamonds were cut to meet a target range of proportions, but not to exhibit maximum visual performance with the understanding that the majority of people searching for diamonds online are focused merely on finding diamonds which have been graded as being “ideal cut” but with the understanding that these same consumers are not aware that there is more to the picture than meets the eye so-to-speak.

Since the gemological laboratories only grade diamond symmetry by taking into consideration the consistency of facet shape and alignment per section, the diamond cutters are able to mass produce “round brilliant ideal cut diamonds” which will achieve the top grades of GIA Excellent or AGS Ideal 0 and thus meet the selection criteria for the majority of online diamond buyers without sacrificing the additional loss of diamond rough which is required to actually achieve the superior visual performance which will be exhibited by a diamond which exhibits a crisp and complete pattern of hearts and arrows… they also won’t have to spend as much time planning the production of the diamond or actually cutting the diamond because each facet will not have to be carefully aligned because the facet-by-facet structure of the diamond is not likely to be evaluated by the majority of online consumers which these diamonds are being produced for.

The reason I know this type of production detail is because I was the principal diamond buyer for Treasures by R.J. and NiceIce.com for more than 25 years and each time I sat down with a diamond cutter to discuss our production needs, we would discuss the degree of planning and the additional expense involved with producing diamonds of the caliber which we expected… and each online vendor has this type of discussion with their suppliers on an ongoing basis, year after year and the nature of the production varies dramatically from supplier to supplier and from vendor to vendor depending on the structure of their business model.  Online diamond vendors who specialize in Round Brilliant Super Ideal Cut Diamonds which exhibit Crisp and Complete patterns of Hearts and Arrows have different production requirements than online vendors who focus on selling round brilliant ideal cut diamonds of a broader spectrum.  The trick is to understand that there are differences, not only in production quality, but also visual performance and subsequently price and then work to find the best diamond options available within the spectrum of quality which you deem to be appropriate for your expectations and budget.

If the diamond is not graded by the American Gemological Laboratory (AGSL) on their Platinum Light Performance grading platform, then it is especially important to be able to view an image of the diamond as seen through an ASET Scope which is designed to provide insight into the diamond cut quality and visual performance of the diamond by demonstrating where in the hemisphere the diamond is attracting and reflecting light back from.  The abbreviation ASET stands for Angular Spectrum Evaluation Tool and the scope is designed to indicate the position of light being reflected by referencing the colors blue, red, green and white.  Blue represents the contrast being exhibited by the diamond due to the observer blocking light from the surface of the diamond, such as when you hold the diamond in front of you to look at it… the technical term for this effect is obscuration and it can be the most dramatic and beautiful effect upon a diamond because contrast is what enables us to see the differences in light reflection created by the facets of a diamond.  The majority of contrast visible within a round brilliant ideal cut diamond results from the arrows pattern which is created by the pavilion main facets located on the underside of the diamond, if the structure of the pavilion main facets is too thin or too wide, then the degree of contrast will be less than optimum and the contrast of the diamond will be less appealing.

The color red as seen in an ASET image represents medium angle light which is the majority of light which a diamond is exposed to and is a direct indicator of how bright the diamond will be… the color green represents the amount of low angle light which is entering the diamond and being reflected back, it is typical of light which is provided by windows or the lower edges of the hemisphere.  White represents the amount of leakage which is occurring within the diamond, this is reflection which is essentially lost due to variances in the facet structure of the diamond.  An Ideal Scope can provide similar insight in terms of the amount of light leakage which is occurring due to variances in the facet structure of a diamond and represents leakage as white areas contrasted by pink areas which are the result of the pink contrast created by the pink cone used within the design of the Ideal Scope.  The primary difference between the two scopes is that one is intended to demonstrate how the diamond is returning the light which it is exposed to throughout the hemisphere of light which it is commonly exposed to and the other is solely designed to determine how much light leakage is occurring.  I consider both instruments to be critical to the diamond selection process and prefer to work with online diamond vendors who readily provide this information because it serves to quickly narrow down the available options and improves the ability to purchase a diamond online which truly exhibits superior visual performance.

With this in mind, I perused the current inventory of diamonds offered by Blue Nile to determine what options appealed to me in terms of having the potential to warrant further consideration based upon the proportions of the diamonds and the characteristics represented on the diamond grading reports.  To begin with, I used the Advanced Options available within the Blue Nile Diamond Search feature as indicated in the following graphic:

As you can see, I set the range for total depth between 59 – 61.8% because this will limit the search results to diamonds which exhibit a suitable outside diameter or “spread” which is a way to reduce the number of diamonds which have been cut too deep in an effort to retain more of the diamond rough crystal.  Round brilliant cut diamonds which have a total depth exceeding 61.8% were cut for maximum retention of diamond rough and not maximum visual performance…

I limited the table diameter of the diamond between 53 – 57.5% which is the original parameters for the zero ideal cut proportions rating as defined by the AGS Laboratory.  Unfortunately there is not a way to further refine the search results by limiting the crown angle of the diamond between 34.3 – 34.9 degrees and the pavilion angle between 40.6 – 40.9 degrees or I would do so… thus we’ll have to consider the crown and pavilion angle measurements for each diamond individually by looking at the lab reports.  The reason for selecting diamonds with crown and pavilion angle measurements within the range stated above is that these two sections are the primary reflective surfaces of the diamond… think of the pavilion angle as controlling how much light will be reflected back towards the observer and the crown angle as the factor which will determine the type of light return in terms of brilliance and dispersion.  If the pavilion angle is too shallow or too steep, the diamond will reflect less light back up towards the observer and will be likely to leak more light out the edges or may appear dark in the center of the stone.  With the understanding that everybody has a preference in terms of the type of light return they like to see from a diamond, I prefer to see more of a balance of brilliance (reflected white light) and dispersion (reflected colored light or fire) and thus I prefer the crown angle and pavilion angle offset indicated above.

I restricted the polish and symmetry of the diamond to GIA Excellent or AGS Ideal because these are indications of the consistency of facet shape and alignment per section (in terms of the meet points of the facets) and the polish is an indicator of how well the surface of the diamond is polished.  Ideally I would also restrict the girdle thickness of the diamond to be between thin and medium or perhaps slightly thick if I had to sacrifice something and availability is limited (which it is always going to be at the upper end of the spectrum for each range of carat weight, in this case 1.00 – 1.49 carats).  Additionally I would limit the culet size (bottom point) of the diamond to either GIA “none” or AGS “pointed” which are different terms to represent the same culet size.

Here are the options which I have selected from the various diamonds which were produced by my search:

1.34 carat, G color, VS-1 clarity round brilliant ideal cut diamond from Blue Nile graded by the GIA as having an overall cut rating of GIA Excellent with faint fluorescence.  According to the GIA the diamond has a total depth of 61.5% with a table diameter of 57% with an average crown angle of 34.5 degrees which is offset by a pavilion angle of 41.0 degrees with a medium to slightly thick, faceted girdle and a small culet.

Since the pavilion angle of the diamond exceeds my preferred range of 40.6 – 40.9 degrees and the girdle thickness is a little thicker than I prefer and the culet size is larger than I prefer, I’d normally not give the diamond a second glance because I’m kind of a snob when it comes to diamond cut quality… but for the sake of this diamond buying tutorial, let’s discuss it because the truth is that the diamond falls within the Top 1% of diamond cut quality when compared to the majority of round brilliant cut diamonds produced on an annual basis… so while this diamond might not meet my personal expectations in terms of being the very best, it is quite superior to the majority of diamonds which are offered by the average brick and mortar jewelry store!

The polish and symmetry of the diamond have been graded as GIA Excellent which is the highest grade available from the GIA for these factors.  The pavilion angle of 41.0 degrees is just a smidge higher than the 40.9 degrees which defines the upper end of the range for my target range of 40.6 – 40.9 degrees and if the spread between the high and low measurements which result in the average pavilion angle of 41.0 degrees are “tight” such as a low of 40.8 degrees and a high of 41.2 degrees then this might be a very pretty diamond which is full of life!  The trick is that we need the additional information which would be provided in a computerized proportions analysis to make that determination… so ask Blue Nile to provide this additional information if the diamond is of interest.

Now because this is one of the Blue Nile Signature Diamonds it is accompanied by an additional report provided by GCAL which is based upon Gemprint Technology.  I like the Gemprint feature on the report because it provides a representation of the “fingerprint” of light return exhibited by the diamond, but I’m personally not a fan of their attempt to represent the visual performance of the diamond because I feel that the platform is lacking in substance in terms of consistency as a scientific methodology for measuring light return… but the report does provide us with an image (above) which shows the shape of the pavilion main facets or the arrows pattern of the diamond and it looks a little thin to me and there is visible differences in the depth of shading for each of the arrows and the tips of the arrows… the arrow heads pictured in the one o’clock, two o’clock, eight o’clock, ten o’clock and eleven o’clock positions are darker and exhibit more contrast than displayed by those in the other positions… and we can see from the hearts image provided that there is some variance in the size and shape of the hearts and from experience I know that the hearts are smaller than they should be based upon my personal preferences and this is an indication of how the bezel main facets and corresponding crown facets are shaped and situated.

So while the diamond is likely to exhibit a nice degree of light return, it is less likely to exhibit the amount of contrast that I like to see from an ideal cut diamond and thus this diamond would not be one which I would select for myself… it is however cut significantly better than the majority of round brilliant cut diamonds available and is likely to be quite pretty… understand that at this level of the game, my goal is to maximize light return, contrast and sparkle factor, so I’m looking for the Top 1/10th of 1% and not just the Top 1% but everybody’s expectations are different, you have to decide what degree of perfection you are looking for and where to draw the line… my job is simply to help you understand the various factors at play in terms of diamond design, diamond cut quality and visual performance and I feel that this is best achieved by walking you through my thought process as if you were sitting at my desk evaluating each diamond on it’s individual merits.

Finally we look at the plotting diagram for the inclusions within the diamond as indicated on the GIA diamond grading report which are indicated as being cloud, needle, feather and natural.  A cloud is simply a group of tiny pinpoint size diamond crystals and a needle is a long, thin diamond crystal… these are nothing to be concerned about.  A feather is a minute fracture within the diamond and in this particular instance, it is nothing to be concerned about because it is miniscule.  A natural is part of the original skin of the diamond rough, it is probably located along the girdle edge of the diamond and is nothing to be concerned about, they are often left on in an attempt to retain diamond weight and have no effect upon the visual performance or durability of the diamond crystal.

Next we have this 1.40 carat, G color, VS-2 clarity round brilliant ideal cut diamond from Blue Nile which is graded by the GIA with an overall cut rating of GIA Excellent and faint fluorescence.  According to the GIA the diamond has a total depth of 61.6% with a table diameter of 57% with a 34.0 degree crown angle which is offset by a pavilion angle of 41.0 degrees with a medium to slightly thick, faceted girdle and no culet.

All right, so we already know that the diamond does not meet my selection criteria in terms of the offset for crown and pavilion angle, but let’s talk about that… my preferred range of 34.3 – 34.9 degrees is based upon my preference for a round brilliant ideal cut diamond to exhibit a relative balance of brilliance and dispersion, but it is possible that you prefer to see more brilliance than dispersion, in which case the shallower crown angle is more apt to be pleasing to your preferences and this would be a good option.

The primary inclusions are indicated as being crystals and needles, so basically we have tiny diamonds that were trapped within the larger diamond crystal as it formed.  Once again if you take a look at the GCAL report which is available off of the diamond details page, you’ll see that the structure of the arrows pattern is similar to the diamond referenced above and that there is a little more inconsistency in the hearts pattern of the diamond which is a reflection of the facets which comprise the crown section.

Next we’ll look at this 1.41 carat, G color, VS-1 clarity round brilliant cut diamond from Blue Nile which is graded by the GIA with an overall cut rating of GIA Excellent with no fluorescence.  According to the GIA this diamond has a total depth of 61.8% with a table diameter of 57% with a crown angle of 34.0 degrees which is offset by a pavilion angle of 41.4 degrees with a medium to slightly thick, faceted girdle and a small culet.  Now if you’re paying attention to the subtle distinctions between the descriptions I’m using to reference these diamonds you’ll notice that the link for this diamond provided above refers to the diamond as a “round brilliant cut diamond” and not a “round brilliant ideal cut diamond” and that is because I rely on the proportions guidelines established by the AGS Laboratory to determine the proportions grade of round brilliant cut diamonds and under that grading platform a diamond with a table diameter of 57% with a crown angle of 34.0 degrees and a pavilion angle of 41.4 degrees would be AGS-1 Excellent and not AGS Ideal 0, thus this diamond does not meet my selection criteria as an ideal cut diamond.

I’m also not fond of the type of light return which I usually see in diamonds with this particular offset of crown and pavilion angle, so I’d pass on this one… but since this is a diamond buying tutorial, we’ll continue on for the sake of argument… the inclusions are indicated as being cloud, needle, pinpoint, all of which are acceptable.  If you take a look at the images for the crown and pavilion sections as provided on the GCAL report, you’ll note that this diamond also exhibits pretty narrow pavilion mains with a higher degree of variance in terms of the consistency of size and shape as well as more variance in the consistency of contrast in the darkness of the arrow shafts and arrow heads.  Additionally there is more variance in the size and shapes of the hearts as indicated within the image representing the pavilion section.

Next we have this 1.42 carat, G color, VS-2 clarity round brilliant ideal cut diamond from Blue Nile which is graded by the GIA with an overall cut grade of GIA Excellent with no fluorescence.  According to the GIA the diamond has a total depth of 61.6% with a table diameter of 56% with a crown angle of 35.0 degrees which is offset by a pavilion angle of 40.6 degrees with a medium, faceted girdle and no culet.  All right, so the crown angle is a bit steeper than my preferred range of 34.3 – 34.9 degrees, but it’s not too far out of whack assuming that the spread between the high and low measurements is acceptable (we’d need a computerized proportions analysis to make that determination) and a slightly steep crown angle often works quite nicely with a shallower pavilion angle like 40.6 degrees… so the diamond is a viable option in terms of the potential for light return in terms of volume.

The primary inclusions are indicated as being cloud, crystal, pinpoint, so nothing to worry about there.  Moving on to the GCAL report, there is better contrast visible in the arrows and less variance in terms of the size and shape of the arrows; but there is a little more variance in terms of the size and shape of the hearts, there is more variance in the shape of the clefts of the hearts and the tips of the hearts are twisting which is a clear indication of Azamet shift which we touched on earlier, but essentially means that the virtual facets of the diamond will be smaller… which means that the flashes of light produced by this diamond are likely to be smaller in size than those produced by an ideal cut diamond cut to a higher level of diamond cut quality and this means a lesser degree of sparkle factor.  Now if you like a lot of reflected white light or brilliance, then this is a good option for you; however if you prefer to see larger flashes of colored light combined with a virtual balance of brilliance and white light, then I’d hold out for something cut a little tighter.

The last option which we have to consider is this 1.45 carat, G color, VS-2 clarity round brilliant ideal cut diamond from Blue Nile which is graded by the GIA with an overall cut rating of GIA Excellent with no fluorescence.   According to the GIA the diamond has a total depth of 61.7% with a table diameter of 57% with a crown angle of 35.5 degrees offset by a pavilion angle of 40.8 degrees with a medium to slightly thick, faceted girdle and a small culet.  The proportions of this diamond are too far out of whack for my personal taste, but here again it is still produced within the Top 1% of the round brilliant cut diamonds which are produced in the average year and the diamond does meet the selection criteria for the AGS zero ideal cut proportions rating.

If you take a look at the plotting diagram of the inclusions provided on the GIA diamond grading report, you will see that the primary inclusions are indicated as being crystals, feathers, clouds, needles and indented naturals… in this particular instance, I would reject the diamond “off paper” (meaning it would not have been brought in for physical evaluation even if the proportions fell within my desired range) because of the extent of the feather indicated in the eight o’clock region of the upper plotting diagram and the stack of tiny feathers which are indicated just below it because of the potential for the feathers to present a durability risk… keep in mind that I’m known for being a “diamond snob” and I just don’t see the reason to take the risk even if it is likely to be minimal, especially when the other characteristics of the diamond do not meet my selection criteria.  If you take a look at the crown and pavilion images provided on the GCAL report, you’ll see that there is a fair degree of contrast between the size and shape of the arrows as well as the dark to light variance in the arrow heads as well as a high degree of variance in the size and shape of the hearts.

This completes my evaluation of the options currently available from Blue Nile within the range of characteristics specified as being the parameters for your quest.  Hopefully the depth of this analysis provides you with some insight into the thought process that goes into selecting a round brilliant ideal cut diamond and will provide you with an outline to establish the criteria for further searches of the Blue Nile Inventory.  If I were to select a diamond from the options currently available from Blue Nile, I’d be inclined to go with either the 1.34 carat or 1.40 carat options as they are closer to my preferred selection criteria and seem to be the most likely to exhibit better light return, but I would want to see a detailed proportions analysis and hopefully some images of the diamond as seen through an ASET Scope, Ideal Scope and a Hearts and Arrows viewer before making a final decision.  As stated previously, Blue Nile could probably request the computerized proportions analysis from the diamond cutter who produced these diamonds and then you could have the diamond shipped to San Diego Gem Lab for further evaluation.

James Allen had nothing currently available within their True Hearts Collection and neither did High Performance Diamonds but I did find this 1.380 carat, F color, VS-1 clarity Signature Hearts and Arrows Diamond from Brian Gavin.  This is an excellent example of the type of diamond which I do look for when searching for diamonds which fall within the spectrum of my diamond selection criteria.  The diamond is graded on the Platinum Light Performance platform of the AGS Laboratory which I find preferable to the grading platform employed by the GIA Laboratory simply because I like the insight provided by the additional light performance analysis which evaluates the diamond using ASET technology, but does so by evaluating the diamond at more than 200 degrees of tilt as opposed to merely the single degree of evaluation provided by using the handheld ASET scope.

According to the AGS Laboratory the diamond has a total depth of 61.6% with a table diameter of 55.3% with a crown angle of 34.9 degrees which is offset by a pavilion angle of 40.6 degrees with a thin to medium, faceted girdle and a pointed culet… so it falls within the center range of proportions which I stated as my preference earlier in this article.  The primary inclusions are a cloud and small feather.

The diamond looks exceptional when viewed through an ASET scope and an Ideal Scope, it exhibits a high degree of blue contrast while exhibiting a lot of red and just the right amount of green with minimal leakage… likewise there is very little white visible in the Ideal Scope image.  The diamond exhibits a crisp and complete pattern of hearts and arrows as indicated by the clarity photograph which clearly shows that there is nice deep contrast in the arrows and the hearts image which shows consistency of shape and size.

Now this diamond is going to cost more than the options we’ve considered on Blue Nile because it is an F color, but also because it is cut to a tighter range of specifications… I’m not suggesting that you purchase it because it likely exceeds your desired price range, but it is an excellent example of what I look for in a diamond.

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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