I’m looking for the best diamond I can buy for an engagement ring for ~$30,000 ($28k – $32k). I’m looking for AGS Ideal / GIA Excellent cut with Hearts & Arrows, a good score on the Holloway Cut Adviser, D to E color, 1.5 – 1.7 carats, VS-2 or higher in clarity. I’m considering [diamonds referenced below] two Crafted by Infinity diamonds from HPD; a couple from Whiteflash; three from Brian Gavin; James Allen doesn’t seem to have much; and of course Blue Nile has many, but I’ve focused in on two which seem the most symmetrical from their GCAL reports. I’m wondering if you have any recommendations or what things I should take into consideration. – David L.
Since extremely well cut diamonds in this weight category are in short supply, I thought I would begin by declaring my top choices and then explain the thought process, that way you can reserve these diamonds if you’re so inclined and then have time to read “the why” behind my choices.
The 1.698 carat, F-color, VS-1 clarity, Crafted by Infinity round diamond from High Performance Diamonds and the 1.705 carat, E-color, VS-2 clarity, Brian Gavin Signature round diamond.
Both diamonds look really good in the ASET and Ideal Scope images, the option from HPD shows “minor” variations in the hearts pattern which is most likely due to the alignment of the diamond to the camera lens… this is a known issue with the person capturing the images for CBI in Antwerp, they job that part of their operation out and the person continually fails to set the diamond properly and set the focal depth correctly, but it appears to be their only option and I have no doubt that it is costing them sales… The hearts appear to be better formed on the pavilion view ASET provided on the lab report, and in my experience as a former CBI dealer, will look great in-person.
The proportions of both diamonds are well within my preferred range and the inclusions are quite acceptable, in fact the inclusions for all of the diamonds presented look perfectly fine.
Now that we have that out of the way, let’s dissect the other options as if you and I were sitting together while I am sifting through a parcel of diamonds which were sent to me for evaluation… The first thing I would do is look over the details on the lab reports, to ensure that the overall cut grade of the diamond, the proportions, and the inclusions meet my selection criteria… check, check, check, with exception of the options from Blue Nile if you’re truly looking for the combination of proportions and optical symmetry that produces the highest volume of light return and the most intense sparkle… more on this later.
For the explanation which follows to make sense, it is important to understand that when a diamond cutter evaluates a piece of diamond rough, it is generally understood that the rough needs to be divided into three sections; one third of the rough should be dedicated to the upper part of the diamond which is the crown section; and two thirds of the rough will be dedicated to the lower section, which is the pavilion; and then there will be a slight adjustment made between the two sections for the girdle edge of the diamond. The diamond cutter has to find the balance between cutting the diamond for light performance, and the need to maximize the yield of carat weight.[separator]
Any adjustment made to either the crown or pavilion sections in terms of depth, needs to be accounted for by offsetting it in other areas of the diamond if the balance of light return is to be maintained and light is going to continue to reflect through the diamond properly… thus there is not one absolute combination of measurements to shoot for.
If the cutter cuts the pavilion depth a bit steep, then they need to adjust the crown height accordingly to maintain the balance between “the mirrors” (facets) of the diamond which reflect light through the diamond and back up towards the observer… the angle of the crown and pavilion facets must also be adjusted if the balance of brilliance and dispersion is to be maintained.
Sometimes the cutters will adjust the angle of the facets as they meet the girdle edge of the diamond, without getting super technical, this is one method of “cheating the stone” to maximize carat weight. The good news is that when these diamonds are viewed through an Ideal Scope, there are always tell tale signs that appear quite obvious to a trained observer. Other reflector scopes such as the ASET and Hearts & Arrows viewers provide additional insight into the degree of optical symmetry and light return potential of a diamond.
A long time ago, before the use of reflector scopes were commonly used to judge optical symmetry, Brian Gavin who is one of my mentors in the business and a former supplier (via his former wholesale division, not Brian Gavin Diamonds) taught me a quick and dirty trick for determining the extent to which the cutter might have cheated the stone… simply take the measurements of the diamond as stated on the lab report, and multiply them using this formula and it will tell you what the carat weight of the diamond would be if everything about the diamond were cut perfectly, which I’ve never actually seen a diamond by the way…
Let’s use the measurements of the 1.698 carat, F-color, VS-1 clarity, Crafted by Infinity round diamond from HPD as the basis for this demonstration. According to the American Gem Society Laboratory (AGSL) the diamond measures 7.66 – 7.68 x 4.73 millimeters. Here are the steps:
Round 1.697387664 off and the estimated carat weight is 1.697 which is pretty darn close to the actual weight of the diamond which is 1.698 carats, so clearly Paul Slegers of Crafted by Infinity did not “cheat the stone” to maximize the yield of carat weight, he was clearly focused on producing the most beautiful diamond possible.
Interestingly enough, the GIA teaches their students to average the minimum and maximum outside diameter of a diamond when estimating the carat weight of a diamond, so you’d add 7.66 + 7.68 = 15.34 divide that by two = 7.67 multiply that by itself 7.67 = 58.8289 and then multiply that by the depth of the diamond 4.73 = 278.260697 = 1.6973902517 and therefore no matter which method you use to estimate the weight of a round brilliant cut diamond, it is clear that Paul didn’t “cheat the stone” as the cutters like to say.
All right, so if use the same formula for estimating the weight of a round brilliant cut diamond to the 1.705 carat, E-color, VS-2 clarity, Brian Gavin Signature round diamond which measures 7.65 – 7.67 x 4.73 mm the estimated weight of the diamond turns out to be 1.69296642015 which we’ll round off to 1.692 carats, so the difference between the actual weight of the diamond and the weight of the diamond by formula is 0.013 carats, so I think it’s safe to say that Brian didn’t cheat the stone either.
All right, so let’s take a look at the other options which you selected, in order of carat weight:
The 1.537 carat, D-color, VVS-2 clarity, ACA round diamond from White Flash, looks great by the numbers, the proportions of the diamond are spot-on, however when I look at the Ideal Scope image provided for the diamond, it looks like it is showing just a little bit of light leakage under the table facet. But I don’t want you to base your opinion of the diamond solely on my interpretation, I recommend taking a good look at the light grey region that is visible along the edge of the table facet, and then compare it to the images provided on this Ideal Scope reference chart, and tell me where you think the diamond falls on that chart which I’ve provided a screen shot of below for quick reference.[separator]
In my opinion, the Ideal Scope image for the 1.537 carat, D-color, VVS-2 clarity, ACA round diamond from White Flash looks pretty similar to the Ideal Scope image featured in the top row of the first column for the Very Good Light Return column on the Ideal Scope reference chart pictured to the left, the only real difference that I see is a slight difference in the contrast settings of the two images. You might be wondering how this is possible since the diamond has a 34.7° crown angle offset by a 40.9° pavilion angle. My guess is that the spread between the high and low measurements that make up the average pavilion depth of 43.3% is a bit broad, because when the pavilion depth gets too steep then the light which enters the diamond doesn’t quite strike the pavilion facets right and the diamond begins to leak light.
Obviously whatever is going on underneath the table facet of this Whiteflash A Cut Above™ diamond is not enough to prevent it from receiving an overall cut grade of AGS Ideal-0 from the American Gem Society Laboratory (AGSL), however at this level of the game I feel that it is the minor differences between diamonds that enable us to choose between them and end up with the best option available.[separator]
Oh by the way, if we estimate the carat weight of this diamond using the formula provided above, it comes out to 1.541 whereas the actual weight of the diamond is 0.004 carats less at 1.537 carats, thus it is clear that the cutter who produced this diamond for Whiteflash did not cheat the stone either.
Moving on to the 1.54 carat, E-color, VVS-1 clarity, Signature round diamond from Blue Nile which has an overall cut grade of GIA Excellent, the crown angle is pretty steep at 35.5 degrees, but it’s a decent offset for the pavilion angle of 40.6 degrees which is on the shallower side of my preferred range. The problem is that when the crown height of 15.5% is taken into account as an offset for the 43.0% pavilion depth, then the proportions of the diamond aren’t actually all that great because we realize that the diamond cutter left a bit too much diamond weight on the top half of the diamond when he divided the diamond rough into sections.
Blue Nile does not provide images of the diamonds which they sell as seen through the various reflector scopes, but I don’t really need them to determine that the optical symmetry of this diamond is not up to par with the likes of Brian Gavin Signature, Crafted by Infinity, or Whiteflash A Cut Above, despite Blue Nile’s claim that all of their Signature round diamonds are “Hearts and Arrows Diamonds”.
Just take a look at the variance in the size and shape of “the hearts” (ahem) which are visible in the clarity photograph of the pavilion section that is provided on the diamond grading report issued by GCAL. Arguably this is photograph is intended to provide details pertaining to the clarity of the diamond, but the hearts pattern is clearly visible, so let’s not quibble about minor details pertaining to whether the light is being filtered by a colored piece of filament paper or not… the hearts vary in size and shape and the width of the pavilion mains which make up the arrows pattern vary substantially in thickness, just take a look at the heart located in the 12 o’clock position to get your bearings.[separator]
Now allow your eyes to move clockwise around the diamond, comparing the shape of each heart to the one located in the twelve o’clock position, and notice how each one of them differs in size and shape. You might also notice a difference in the length and width of the pavilion main facets which make up the eight pointed star that extends outwards from the center of the diamond to the girdle edge between each heart.
Notice how the tips of the arrows pattern of the diamond in this photograph are fading out in some places and being “paddled” in others by too much dark space? It’s like the outer edge of the diamond fluctuates from light to dark with no degree of consistency… Just look at the difference between the arrow located at 2:30 which is crisp and clear, and then the arrowhead located in the next position running clockwise around the diamond; then look at how the one in the 11 o’clock position which is almost fading out entirely. The most likely cause of this type of irregularity is the variance between the high and low measurements which result in the average pavilion angle of 40.6 degrees.[separator]
Interestingly enough, if you run the formula to estimate the weight of a round brilliant cut diamond on this 1.54 carat, E-color, VVS-1 clarity, Signature round diamond from Blue Nile you’ll discover that the measurements indicate that the diamond should weigh 1.52 carats by formula, so where is the extra two points of diamond weight coming from? My guess is that it’s hidden in the crown height of the diamond, and apparently was done so at the expense of a proper pavilion angle, resulting in the variance in the obstruction pattern that is visible above. Is all of this beginning to make sense?
Next we’ll take a look at the 1.557 carat, E-color, VS-1 clarity, Crafted by Infinity diamond which you found on High Performance Diamonds. It has an overall cut grade of AGS Ideal-0 with a crown angle of 34.3 degrees which is offset by a pavilion angle of 40.7 degrees and the crown height and pavilion depth measurements are great. The photographer for Crafted by Infinity managed to capture a very nice picture of the hearts and arrows pattern, and the diamond looks spot-on in all of the reflector scope images… and when I run the formula to estimate the carat weight of the diamond, I get a difference of only 0.014 carats. So why didn’t I select this as one of my top two diamonds?[separator]
Because personally I’d buy the 1.698 carat, F-color, VS-1 clarity, Crafted by Infinity round diamond from HPD or the 1.705 carat, E-color, VS-2 clarity, Brian Gavin Signature round diamond because they offer a larger carat weight for less money, and they are all going to exhibit a comparable volume of light return and the same sparkle factor… which means that if either the 1.698 or 1.705 carat diamonds weren’t available, then this 1.557 carat, E-color, VS-1 clarity, Crafted by Infinity diamond would definitely be a contender!
Moving on in order of carat weight, the next diamond up for review is this 1.700 carat, E-color, VS-2 clarity, Whiteflash A Cut Above round diamond, which is showing a fair amount of grey along the edge of the table facet in the Ideal Scope image, if you compare that image to the diamond located in the 2nd Row of the Good category for the Light Return images featured on the Ideal Scope reference chart, I think you’ll find that they look pretty close, but the one featured on the reference chart shows just a bit more light leakage. Note that if you click on the Ideal Scope image provided on the diamond details page by Whiteflash, the signs of light leakage become much more apparent.
Here again, what is most likely causing the light leakage that is apparent along the edge of the table facet in the Ideal Scope image is the spread between the high and low range that makes up the average pavilion depth of 43.4% that is stated on the diamond grading report.[separator]
Now if you look closely at the pavilion mains of the diamond on the ASET diagram provided on the diamond grading report, and compare those to the pavilion mains for the three diamonds which I’ve given the green light so far, you should be able to see that the pavilion mains of the diamond appear thinner and there is a bit more space separating the hearts from the arrowheads positioned beneath them. Hmmm, something to think about.
Interestingly enough, if you take the measurements for the 1.700 carat, E-color, VS-2 clarity, Whiteflash A Cut Above round diamond as stated on the diamond quality document issued by the AGSL and run it through the formula for estimating the carat weight of a round brilliant cut diamond, the estimated weight comes out to 1.678 carats, which is a difference of 0.022 carats which is just a bit more of a difference than exhibited by the 1.54 carat, E-color, VVS-1 clarity, Signature round diamond from Blue Nile reviewed above.
So where is all that extra carat weight hiding? I’ll give you a hint… Take a real close look at the difference in the contrast between the pink and red colors exhibited in the Ideal Scope image along the edge of the diamond, between the sections of kite shaped bezel facets, and the triangular upper girdle facets that are located alongside them on the edge of the diamond. Do you see how light pink the kite shaped bezel facet positioned at the tip of the green arrows are in comparison to the darker red upper girdle facets which are located at the tip of the yellow arrows?
Now take a look at the Ideal Scope images for the ideal cut diamonds which you asked me to review from Crafted by Infinity and Brian Gavin, they don’t exhibit that kind of contrast along the girdle edge of the diamond… do they? And this is one more reason why I’ve chosen those diamonds over the other options which you presented.[separator]
The next diamond on your list is this 1.708 carat, E-color, VS-1 clarity, Brian Gavin Signature round diamond, which exhibits an Ideal Scope image that looks a lot like the one featured in the 2nd row of the Excellent Light Return category on the Ideal Scope reference chart, so we know that the 43.3% pavilion depth is not a factor and the pattern of hearts and arrows looks fantastic, as does the ASET image.
So why didn’t I pick this diamond? Here again it is simply because I’m more inclined to go with the 1.698 carat, F-color, VS-1 clarity, Crafted by Infinity round diamond from HPD or the 1.705 carat, E-color, VS-2 clarity, Brian Gavin Signature round diamond because they offer the same perceptible size and overall look for less money. And once again, if either of those diamonds were not available, then I’d be apt to choose this or the 1.557 carat, E-color, VS-1 clarity, Crafted by Infinity diamond because they are both cut like a dream.
The last diamond on your list in order of carat weight, is this 1.71 carat, E-color, VVS-2 clarity, Blue Nile Signature round diamond, which presents us with another opportunity to learn something about GIA Excellent cut diamonds, primarily that not all diamonds graded as GIA Excellent are actually cut excellent… and that is because the symmetry grade is based upon meet point symmetry and not optical symmetry.
Do you see how “the hearts” (ahem) located in the relative two, three, and ten o’clock positions are half light and half dark in tone? That’s a sign that the light is not being fully captured and reflected off of the pavilion facets, which seems kind of strange since the pavilion depth of the diamond is 43.0% but keep in mind that the measurement stated on the diamond grading report is the “average measurement” and that this concept is further complicated by the fact that the GIA then rounds off the average measurement, so who knows what the actual range between the high and low measurements for the pavilion actually are, but clearly something is going on.[separator]
Obviously it’s not always easy to determine the minor differences in cut quality between Brian Gavin, Crafted by Infinity, and Whiteflash A Cut Above diamonds, solely by the details provided on the diamond grading reports that are provided for each diamond, however it is possible to detect minor differences between the diamonds using reflector scopes such as the ASET, Ideal Scope, and a Hearts and Arrows viewer.
With this type of detailed information being provided by Brian Gavin, High Performance Diamonds, and Whiteflash, you’ll be able to narrow down the options based upon the subtle differences in optical symmetry, and select whichever option appeals to your personal sense of balance… I look forward to seeing which diamond you select, and by all means please send me a picture of the completed ring!
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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