James Allen Diamonds is a popular online source for diamonds because Jim and his staff provide a great level of customer service and a large selection of diamonds in a variety of cut qualities in an effort to appeal to the broadest market share possible. I tend to ignore the non-ideal cut options offered by James Allen because my niche within the industry has always been the extremely small world of ideal cut diamonds that represent the Top 2% of the annual production for round brilliant cut diamonds. James Allen offers two lines of round brilliant ideal cut diamonds under the category of James Allen True Hearts and Ideal, so what’s the difference between the two lines?
Before we get too far along, I want to mention that only a small percentage of “ideal cut diamonds” actually fall within the selection criteria that I relied on when I was the diamond buyer for Nice Ice, these are what are often described as “super ideal cut diamonds” because they are cut to the middle of the range of parameters designated by the American Gem Society Laboratory (AGSL) for their zero ideal cut proportions rating. Peter Yantzer, Director of the AGSL, once asked me what my proportions criteria was and when I defined it for him, he said “Ah yes, the sweet spot!”
The “sweet spot” as Peter so aptly referred to it is pretty much what Marcel Tolkowsky defined as the perfect proportions for optimized light return in a round brilliant cut diamond in his works “Tolkowsky’s Diamond Design” which was published in 1919, but it is expanded to include the impact of a girdle edge which is something he never took into account in his calculations. Refer to my article 15 Seconds to Diamond Buying Success for detailed information regarding my preferred range of proportions.
Needless to say the majority of online diamond vendors do not limit their inventory of ideal cut diamonds to the limited range of proportions which I consider to actually be ideal cut, so when you search for ideal cut diamonds on James Allen and other web sites, it is necessary to use the Advanced Options feature to limit your search to James Allen True Hearts & Ideal round brilliant cut diamonds with a total depth between 59 – 61.8% and a table diameter between 53 – 58% with GIA Excellent or AGS Ideal polish and symmetry as indicated in the screenshot featured at the beginning of this page which I used to search diamonds weighing between 1.10 – 1.20 carats, G/H color, and VS-2 clarity. If you’d like to save a little bit of time and not have to set these parameters for yourself, you can click this link to use my search criteria to find diamonds on James Allen and then merely adjust the range for carat weight, color and clarity to suit your preferences.
Using the advanced options to limit the range of total depth, table diameter, polish and symmetry, will significantly reduce the number of options and dramatically improve the odds of finding an ideal cut diamond that exhibits the highest volume of light return and is as bright and sparkly as it can be, but you also need to narrow down the options further by looking at the proportions indicated on the diamond grading reports and focus on diamonds which feature a crown angle between 34.3 – 34.9 degrees with a pavilion angle offset that is between 40.6 – 40.9 degrees to really nail things down.
Now this is a simple matter of geometry, the fact is that 40.6 – 40.9 degrees is the optimum range for reflecting the maximum volume of light back up through the upper half of the diamond, and keeping the crown angle offset between 34.3 – 34.9 degrees tends to produce a virtual balance of brilliance and dispersion which is the white and colored sparkle or “fire” that that is created by the facets of a diamond.
Very slight adjustments to the crown and pavilion angle measurements are acceptable provided that they are not too extreme, for instance dropping the crown angle down as far as 34.0 degrees is fine provided that the pavilion angle remains within the range specified above, but it tends to be best if the pavilion angle is on the steeper side of the range, such as within the range of 40.8 – 4.09 degrees and this will generally only slightly affect the balance of brilliance and dispersion reflected by the diamond.
The most critical reflective surface is the pavilion angle and I generally don’t like to see it dip below 40.6 degrees, nor higher than 41.0 degrees because it is likely to have a significant impact upon the volume of light return and can result in a higher rate of light leakage. With all of these considerations taken into account, let’s take a look at the five James Allen ideal cut diamonds which remained viable options after I tweaked the advanced options feature to suit my preferences.
In order of carat weight and color, the five diamonds which we’re going to evaluate in-depth from James Allen are as follows:
Try to keep in mind that all of these diamonds represent options which are well within the Top 2% of the annual production for round brilliant cut diamonds, and represent the best that the diamond industry has to offer… but the reality is that some options will be more desirable to me than others based upon their characteristics.
The first thing that caught my attention about this 1.116 carat, G-color, VS-2 clarity, James Allen Round Ideal Cut Diamond is that while the lab report is dated October 11, 2013 the diamond is not graded on the AGSL’s Proprietary Light Performance grading platform which uses Angular Spectrum Evaluation Technology to measure the brightness of a diamond and provides some insight into the optical symmetry of the diamond via an image which appears in the middle of the report.[separator]
This is a scenario which I always find a bit perplexing because the flap pictured on the right side of the Diamond Quality Document (DQD) clearly indicates that the diamond received a zero grade for Light Performance and the diamond has an overall cut grade of AGS Ideal-0, absent the presence of an ASET image.
This raises the question in my mind as to whether the cutter who listed the diamond with James Allen for representation simply didn’t want to pay the few extra dollars that the Light Performance grading report costs, or was there something about the ASET results that led the cutter to believe that the diamond would best be marketed with the limited information provided on this version of an AGSL DQD?
And since the crown angle of this diamond is only 34.1 degrees offset by a pavilion angle of 40.7 degrees, I’m inclined to simply pass on it and move on to other options which don’t raise these kind of concerns.
Things are looking much better for this 1.138 carat, H-color, VS-2 clarity, James Allen True Hearts Diamond which is graded on the ASET based Light Performance grading platform from the AGSL. The red, green and blue colored ASET image which is visible in the center of the DQD pictured to the left provides me with a clear indication that the pattern of light return is evenly distributed and symmetrical. The proportions of the diamond are well within my preferred range and the primary inclusions consist of different types of diamond crystals which are simply smaller diamonds that were trapped within the larger diamond crystal as it formed. The pattern of hearts and arrows provided by the photographs featured on the diamond details page look great, with only very minor variations in size, shape and just a little twisting in the tips of the hearts. This is a diamond that I would purchase myself.[separator]
This 1.14 carat, H-color, VS-2 clarity, James Allen Round Ideal Cut Diamond is graded by the GIA with an overall cut grade of GIA Excellent. The GIA does not have access to ASET because it is a technology which is proprietary to the AGSL and thus we don’t have any indication as to the brightness level or pattern of light return provided by this diamond. Now this diamond is likely to be one of those rule benders that doesn’t meet my selection criteria, but might still be an interesting diamond only because the total depth of the diamond is 60.3% and that combined with the 80% lower girdle halves is likely to make it a beautiful looking diamond despite the extremely shallow crown angle of 33.0 degrees and the slightly steep 41.0 degree pavilion angle. This is one of those scenarios where I’ve seen it result in an exceptional looking diamond, and also seen it fail miserably in comparison to ideal cut diamonds with tighter proportions.[separator]
Since the price of the 1.138 carat, H-color, VS-2 clarity, James Allen True Hearts Diamond is only $270.00 more than this 1.14 carat, H-color, VS-2 clarity, James Allen Round Ideal Cut Diamond with questionable proportions, I’m inclined to pass on it and opt for the option which offers more balanced options overall.
This 1.148 carat, H-color, VS-2 clarity, James Allen True Hearts Diamond has great proportions which are well within the scope of my preferred range, however just like the 1.116 carat, G-color, VS-2 clarity, James Allen Round Ideal Cut Diamond referenced above, it is not graded on the AGSL’s Light Performance grading platform which provides ASET results and that gives me pause. The only difference in my mind is because this one exhibits a very nice pattern of hearts and arrows![separator]
The presence of a crisp and complete pattern of hearts and arrows is a clear indication that the optical symmetry of the diamond is excellent because the pattern will not appear properly if there is any major variation in the size, shape and spacing of the facets… so this diamond remains of interest even in the absence of an ASET image.
The primary inclusions consist of small diamond crystals and clouds of pinpoint size diamond crystals, I can see from the high resolution video of the diamond provided on the diamond details page that the most prominent of these are three tiny diamond crystals located within the table facet. While these might seem readily visible when you manually rotate the diamond to locate them, try to keep in mind that the standard level of magnification for diamond clarity grading is 10x and the diamond is being viewed using 30x – 40x magnification throughout the video in order for you to be able to see it clearly on your computer monitor.
This 1.160 carat, G-color, VS-2 clarity, James Allen Round Ideal Cut Diamond is definitely worthy of consideration, but you can see by the lack of symmetry within the colored pattern of distribution represented on the ASET image that there is some variation in the pattern of brightness exhibited by this diamond. This is not necessarily something to be alarmed about, but if I were trying to choose between two diamonds of seemingly equal diamond cut quality and characteristics, and one of them exhibited a pattern that was more precise like the one featured within the 1.138 carat, H-color, VS-2 clarity, James Allen True Hearts Diamond referenced above and this one, I’d be inclined to go with the 1.138 carat which appears to have slightly better optical symmetry. This diamond however is still worthy of consideration, it’s just a matter of considering the minute details.[separator]
It is not always a simple choice to decide between buying a James Allen True Hearts Diamond or one of the round brilliant ideal cut diamonds offered by James Allen, so I recommend using my preset criteria to search for a diamond on James Allen and take some time to evaluate the individual characteristics of each diamond in this order to select the best diamond from the options presented:
And of course if you’d like my assistance evaluating the options which are available, please take advantage of my Free Diamond Concierge Service!
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)
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