Judge Diamond Visual Performance for Stunning Sparkle 2021

Black by Brian Gavin Diamond Visual Performance.

Black by Brian Gavin Diamond Visual Performance.

"Can you explain how to judge diamond visual performance online? I'm having difficulty deciding between a few since I can't view the stones for performance. Thanks in advance and for all the useful advice you provide." — Dave.

In the first place, it's easier than you might think to judge diamond visual performance online. Consequently, you can tell a lot about a diamond based on the information provided by the two vendors you reference in your email:

In that case, let's take a look at the factors that dictate light performance.

Characteristics of Diamond Visual Performance:

Black by Brian Gavin Diamond Visual Performance.

Black by Brian Gavin Ultimate Visual Performance.

The first thing to remember is that your diamond's sparkle factor and light performance depend on the cut quality. That might seem rather obvious, but there is more to the picture than meets the eye.

Under those circumstances, most people make a critical mistake by only relying on the diamond grading report. In that case, their perception of cut quality depends on the cumulation of proportions, polish, and symmetry grades.

Those factors are essential to diamond visual performance but do not account for optical precision or Azimuth Shift. Consequently, the overall cut grade on the lab report only takes the following factors into account:

Major gemological laboratories like the AGS and GIA do not evaluate Optical Precision when determining the cut grade of a diamond. That seems counterintuitive since it has a significant impact on visual performance.

Fine-tune Your Search for Diamond Visual Performance:

It helps to know what you're looking for if you're searching for diamonds online. Otherwise, you're going to waste a lot of time sifting through thousands of options with subpar performance.

It's also important to realize that the AGS Ideal and GIA Excellent classifications represent a range or spectrum of inclusion. Under those circumstances, it makes sense to focus on the middle of the spectrum:

  • Total depth between 59 – 61.8%.
  • Table diameter between 53 – 58%.
  • Crown angle between 34.3 – 35 degrees.
  • Pavilion angle between 40.6 – 40.9 degrees.
  • Girdle between 0.7% thin to slightly thick.
  • Culet: GIA "none” or AGS "pointed” (same thing).
  • Polish of AGS Ideal or GIA Excellent.
  • Symmetry of AGS Ideal or GIA Excellent.

Any variation from the proportions above may significantly reduce the diamond visual performance. Be that as it may, the degree of optical precision will also influence the sparkle factor.

Perspective Is the Pinnacle of Understanding:

In a moment, we're going to look at the four diamonds that David referenced explicitly in his email. We're going to walk through the selection, or rather the elimination process.

First, we'll look at the proportions, polish, and symmetry grades of the diamond as outlined above. Then we're going to get into the nitty-gritty hidden factors of evaluating diamond visual performance.

In that case, we'll look at the images of the hearts and arrows pattern. We're also going to evaluate the ASET and Ideal Scope images. But first, I want to remind you that these four diamonds have an overall cut grade of AGS Ideal or GIA Excellent.

Under those circumstances, they are among the Top 1% of the annual production for round brilliant cut diamonds. So, they're all excellent options in their own right, but we're looking for "the one" that is the Cat's Meow.

Option #1 - Diamond Visual Performance Evaluation:

The first diamond to consider is a 1.62 carat, H-color, VS-2 clarity, GIA Excellent cut round diamond from James Allen. Under normal circumstances, the filters I have in place would preclude this diamond because the 62.3% total depth is steeper than I prefer.

In that case, you're paying a premium for diamond carat weight hidden in total depth instead of the visible outside diameter. The 41-degree pavilion angle is also too steep and will not produce as much light return as a pavilion angle between 40.6 - 40.9 degrees.

Using Ideal Scope to Judge Diamond Visual Performance.

Ideal Scope for James Allen GIA Excellent Cut.

If this client did not ask about this diamond specifically, we would not be discussing it. After all, my presets for total depth and table diameter would have prevented me from seeing this diamond in the first place.

Consequently, the light pink and semi-translucent areas visible under the table facet indicate a moderate amount of light leakage. In that case, the 41-degree pavilion angle is a factor, but so is the degree of optical precision, as will be shown below.

This link contains the presets we use to Search for James Allen Diamonds. In that case, you only need to verify that the crown/pavilion angle offset is within the range we recommend above.

Use an H&A Scope to Judge Optical Precision:

Evaluating Diamond Visual Performance Using Heart Pattern.

Standard Ideal Cut Diamond from James Allen.

The Hearts image shown here indicates a variance in the size and shape of the hearts. Simultaneously, the tips of the hearts are twisting and bleeding into the little arrowheads in the middle.

That is an indication that there is a difference in the length of the lower girdle facets. There is also likely an Azimuth shift, which is a variance in the facets' alignment.

Consequently, it requires a lot of skill to align the diamond facets properly from the perspective of 360-degrees. Not only that, but it can also take up to 4X longer to polish a diamond to exhibit a higher degree of optical precision.

That is why James Allen True Hearts Diamonds cost more than their standard ideal cuts. When judging diamond visual performance online, remember that the sparkle factor is higher when there is less Azimuth shift. The more precise alignment of the facets will produce more virtual facets, which creates a more vivid and intense sparkle.

Through the Kaleidoscope of Virtual Facets:

How Virtual Facets Contribute to Diamond Visual Performance.

Virtual Facets the Building Blocks of Sparkle - AGSL

Virtual facets are internal reflections of light similar to what you might see when looking through a kaleidoscope. Only in this case, the various shapes result from light reflecting through the overlapping facet pattern.

In that case, you'll see more sparkle in hearts and arrows diamonds with more precise patterns. Not only that, but the sparkle factor will be more bold, vivid, and intense. Since the lack of consistency in the hearts' pattern creates light leakage, I would reject this diamond.

Finally, the diamond's primary inclusions consist of cloud, crystal, feather, needles, which are acceptable. The types of inclusions you want to avoid are bruises, cavities, chips, etch channels, knots, and laser drill holes.

Judging Diamond Visual Performance - Option #2:

Diamond Visual Performance Ideal Scope.

Ideal Scope James Allen GIA Excellent cut diamond.

The second diamond on the list is a 1.66 carat, I color, VS-2 clarity round ideal cut diamond from James Allen. This diamond would typically not cross my path because the total depth is 62.1%.

Nevertheless, this diamond is more interesting because the AGS Light Performance grading platform is more insightful than what the GIA provides.

In this case, the 35-degree crown angle is a good offset for the 40.9 degree pavilion angle. Consequently, that sets the stage for a high volume of light return and a virtual balance of brilliance and dispersion.

The Ideal Scope image reveals a moderate amount of light leakage, as evident by the light pink and semi-translucent sections. This amount of leakage is typical of most standard ideal cut diamonds because they lack a higher degree of optical precision.

Inconsistent Hearts' Pattern:

Irregular Hearts due to variations in Optical Precision.

James Allen GIA Excellent Cut Diamond (not H&A)

Despite the proportions, there is a fair amount of inconsistency in the hearts' pattern. Specifically, you'll see that the hearts' are different sizes and shapes. Plus, the space around each of the hearts' is inconsistent, creating some of the leakage shown above.

If you look closely, you will also see that the hearts' tips appear to be twisting. That indicates a difference in the length of the lower girdle facets. Our in-depth tutorial on hearts and arrows diamonds will explain the reason.

The plotting diagram on the lab report indicates the presence of crystals. That means that the larger diamond crystal absorbed tiny diamonds as it formed. In that case, the inclusions are of no consequence, and I'm inclined to keep this diamond on the list.

Option #3 - Review of Diamond Visual Performance:

Diamond Visual Performance Ideal Scope Very Good to Excellent.

Very Good Ideal Scope James Allen GIA 3X.

The third option is this 1.68 carat, I-color, VS-2 clarity, round ideal cut diamond from James Allen. The AGS Laboratory also grades it on the Platinum Light Performance grading platform with an overall cut grade of AGS Ideal-0.

The total depth of 62.2% is grounds for automatic rejection based on the criteria I established at the beginning of this article. However, the 34.9 degree crown angle is a good offset for the 40.8 degree pavilion angle.

In that case, the diamond might exhibit a high volume of light return and a virtual balance of brilliance and dispersion. The Ideal Scope image certainly looks better than the other two options from above. If you look at this Ideal Scope reference chart, I think you'll agree that it falls somewhere between very good and excellent.

The Effect of Optical Precision on Light Performance:

Evaluating Diamond Visual Performance Using H&A Scope.

James Allen GIA Excellent Cut H&A Scope.

As you can see, there is more consistency in the size and shape of the hearts. There is only a little bit of twisting visible in a few hearts and only slight variance in size and shape.

However, the hearts' pattern still lacks the kind of consistency that produces exceptional light performance. That is why the table facet lacks the consistency of hue and saturation in the Ideal Scope image above.

Hopefully, you are beginning to see the effect of optical precision on diamond visual performance. Significant variations in the size, shape, and spacing of the hearts will create light leakage. For that reason, I think you should limit your search to hearts and arrows super ideal cut diamonds.

Advanced ASET Insight into Diamond Visual Performance:

Brian Gavin Signature Diamond Visual Performance ASET Map.

Advanced ASET for Brian Gavin Diamond.

The fourth option is this 1.726 carat, I-color, VS-1 clarity, Brian Gavin Signature diamond. The proprietary light performance grading report from the AGS Laboratory features the Advanced ASET 30/40 map.

The additional data that Advanced ASET provides makes it easier to judge diamond visual performance. However, I still like to see an actual photograph since the lab report's ASET map is computer-generated.

In that case, you can't use the ASET map to determine the extent of light leakage Fortunately, Brian Gavin provides photographs of the diamond as seen through an ASET and Hearts & Arrows Scope.

When we combine those images with the insight that the high-resolution video offers, it's evident that this diamond is the best choice.

How to Judge Diamond Visual Performance Using ASET

ASET for Brian Gavin Signature Diamond.

High Resolution Video for Brian Gavin Signature Diamond.

Ultra-high Resolution Video for Brian Gavin Diamond.

Diamond Visual Performance is a Factor of Optical Precision.

Optical Precision of Brian Gavin Signature Diamond.

Todd Gray

About the author

A mad scientist with a passion for improving diamond cut quality to maximize light performance and sparkle factor. I speak geek in degrees of optical precision between bouts of freediving. My ghostwritten ramblings haunt the rabbit holes of information found on many diamond vendor sites. Diamond buyer, author, consultant, errant seeker of deep blue water.

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    1. Unfortunately it is not as easy to use proportions measurements to judge the potential of a cushion cut diamond for visual performance as it is for a round brilliant ideal cut diamond… cushion cut diamonds have much more variance in the overall design structure from manufacturer to manufacturer. In addition, the shape uses four symmetrical sides as part of the structure as opposed to a round which is equally symmetrical by section. Thus while the proportions of a cushion cut diamond are certainly part of the consideration, it is a much more in-depth puzzle in terms of the pieces and each factor plays a part in changing how each part is further considered. May I help you look for a cushion cut diamond Drew? Let me know the parameters in terms of carat weight, color and clarity and I’ll be happy to try and assist.

      1. Thanks, Todd. I responded via email but I’m not sure that worked. Below is my response:

        I’m not actually sure what I’m looking for at the moment (haha). My girlfriend has shown me some of the rings she likes via pinterest, etc. and they include both round and cushion cut diamonds – some with halos, some without. From what I’ve seen and researched, the round seems to put off the most light but I think she tends to lean more towards that square-ish shape. I saw a round diamond in a square-ish halo setting this weekend and so I had the thought to open up the search to round diamonds. Your site gives great advice as far as round diamonds are concerned but I’m a little lost in looking for a cushion. I’ve seen some other information online that explains how to read the ASET graphs and kind of what to look for as far as light leaking, etc. But I just wasn’t sure if there were exact proportions like you gave for round diamonds that applied to cushion cuts.

        If you’re willing to help in the search, that’d be great, but I am kind of enjoying the “hunt” myself. I just don’t know where to look really. As far as carat weight goes, I’d consider anything from .75 to 1.05. For color, I’m leaning more towards H and above and for clarity, VS2 and above. Clarity isn’t a huge deal for me as long as I can’t easily spot an inclusion or the inclusion isn’t visible from the top.

        Thanks,
        Drew

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