Diamond, Newsletter

PriceScope and GCAL Webinar: GCAL 8X® and Why Diamond Cut is Important

Dave Atlas, cut grade industry legend, and Angelo Palmieri, chief developer behind the GCAL 8X® cut grade standard, discuss and debate the significant importance of diamond cut and the 4 Cs to a sophisticated audience of diamond consumers.

Under appreciated by many, but certainly the most important of the 4 Cs, diamond cut is one of the biggest influences in attracting a consumer’s eye and closing the sale.

Be able to explain to your customers how cut quality affects a diamond’s light performance and GCAL’s 8X ultimate cut grade.

The slides and rough transcript of this webinar can be found below.

GCAL was founded in 2001, and started with a simple and straightforward mission, which was to provide the most accurate and consistent gemological services, with uncompromising integrity and unparalleled customer care.
Fundamental to the founding vision of GCAL, is our 4C’s consumer guarantee, which makes us accountable and responsible for every certificate we produce. Because GCAL is the only diamond or gemstone lab with a guarantee, GCAL issues a certificate, while all other labs issue reports that disavow any responsibility for their work product.
Additionally, GCAL is the only ISO 17025 Accredited Forensic Gems and Jewelry Lab in the world.  And while it may sound fancy, let me tell you why it matters to you.  ISO 17025 is the global standard for testing labs in all industries.  The standard ensures technical competency which is assessed by annual, independent audits, conducted by third party scientists.  One brief example…every day since 2008, which is when we were first accredited, we have verified every instrument in our laboratory with certified reference materials…our scales are verified with master diamonds and NIST traceable and certified weights,.. our precious metal analyzers are verified against silver, gold, platinum, and palladium reference materials… our imaging systems are checked with master diamonds to ensure the consistent brilliance measurements are captured….when new versions of hardware are released or upgraded in the lab, we ensure they are producing repeatable results to previous generations… and while our tolerance for verification may decrease (as resolution increases), the expected value targets remain. 
As most of you know, GCAL is headquartered in 580 Fifth Avenue in NYC – we recently expanded our operations and now occupy 1.5 floors in 580, including the entire 27th floor.  We also own and operate Gemprint, Palmieri’s Market Monitor, and recently partnered with v360 to open a dedicated NY service center for diamond gemstone and jewelry videos and photography. 
Here is a brief overview of the different products we produce. From natural to lab grown, print to digital, full certs, mini certs, cards and tags, we offer a wide range of products that serve our customers.
As I mentioned before, we certify loose diamonds, gemstones, and finished jewelry…backed by our guarantee and ISO accreditation. All grading is done in the US, RJC Certified, and SCS accredited…offering diamond measurements and testing, Gemprint, grading, light performance, photomicrographs, 360 video and laser inscription.
Cut is the most controllable of the 4C’s…it is what transforms a lifeless rough crystal into the brilliant polished diamond we all cherish…it is what unlocks the beauty of a diamond, and it is what sets premium manufacturers and retailers apart from their competitors.
GCAL has been issuing cut grades on all shapes for the last 15 years….and every shape is assessed against proportions, finish, and light performance. On the right, you will see our integration chart of how each cut grade is achieved…and until April 2021, our cut grade went from Poor to Ideal.
Here is an example of a VG Oval.
Here is an example of an Ideal Round with H&A.
And in April 2021, we launched the 8X Cut Grade for RB, which represents the top end of Ideal, or Super Ideal. And in June 2022, we launched 8X for Oval and Princess.
Common misconceptions…cut quality can be judged by proportions alone. Proportions alone can be a great rejection tool, but not a great acceptance tool. Here you see a well proportioned RB- in fact it has 8X proportions – everything looks great. But now we see the brilliance, with leakage under the table. And we also see the optical precision is good at best.
Another one…and believe it or not, many people in the diamond trade believe this…Triple EX and H&A are the same. As you can see on the screen, they are clearly not.
Another misconception… ray traced images can tell the whole story. But you cannot assess that this stone is hazy from a ray trace. Here is an excellent one for comparison. In fact, these stones were in the same order, submitted for light performance – similar proportions but very different appearance. And this was easy to see in person as well.
Another misconception…all images on reports are actual images. Definitely not true. Beware of stock images. We now all have the tools and technology to take an actual image. In fact, every qualitative or assessment image you see on the GCAL Certificate is an actual image/video of your diamond. We spend a great deal of time and resources to ensure every picture and video we take accurately depicts the diamond on our certificate.
One of the most significant trends we have seen is the rise of Fancy shapes. 2020 was the first year on record where Rounds accounted for a minority of the submissions. In fact, since 2020, Rounds account for only 45% of the submissions, above 1 carat.
With the rise in popularity of lab grown, and the relatively less expensive cost of the rough material, we are starting to see a rise in custom, unique shapes. Here you see a CVD crystal, cut into the shape of Texas, and one of a teddy bear.
Another trend is the rise of online shopping and research. Consumers are more educated, doing more research, and in many cases, are more knowledgeable than the sales associates selling them diamonds.
Another trend is the technological advancement across diamond factories, on a global scale. The equipment, technology, scalability, and craftsmanship displayed by the premier diamond cutting firms is remarkable. It has led to vast improvements in cut quality over the years.
It has also led to the predicament we are in now – if 75-80% of Round diamonds achieve an Excellent Cut Grade, how we can distinguish the best?
The parameters of Excellent Cut are simply too wide. If your aim is to purchase an excellent cut diamond, you cant be sure what you’re going to get.
So we set out to create the most comprehensive and stringent performance-based cut grade that exists in the market. Simply said, to aim for the best. With 8X, you’ll hit the bullseye every time.
Before we go into the details of the 8X cut grade, we’d like to share a one-minute video that helps tell this story. It has now been viewed over 200,000 times on YouTube and is free to use on anyone’s website.
The 8X Diamond Cut Grade
As previously mentioned, we launched 8X Round Brilliant in April 2021…Oval and Princess in June 2022. And we have plans to launch 8X Cushion and Radiant in 2022, and the balance of classic Fancy shapes in 2023.
We are also launching co-branded and proprietary 8X shapes, as seen here with the Round 10 H&A by JannPaul. If our mission with 8X is to identify and distinguish the highest performing stones, then proprietary/precision shapes must also be included in the standard. We will be working with manufacturers to set and define standards and tolerances for each unique shape.
This is the 8X Certificate for Round diamonds.
The GCAL 8X Cut Grade assesses eight critical factors of cut quality. As you see here, the 8X cut grade can be viewed as 3 broader categories: Physical Excellence (which is comprised of Polish, Symmetry, and Proportions), Light Performance Excellence (which is comprised of Optical Brilliance, Fire, and Scintillation), and Optical Excellence (which is comprised of Optical Symmetry and Hearts & Arrows) for Round diamonds. And all 8 must achieve a grade of Excellent to qualify as an 8X diamond.
Let’s quickly go over each of the 8 Xs. First is Polish. We are assessing the diamond surface, and the freeness of scratches, nicks, pits, dop, white polish, and many other features.
Here we see a fine scratch on the table facet. This is the difference between a Very Good and an Excellent. It doesn’t make a big impact on the performance, but imagine you’re buying a brand new sports car. You don’t want a scratch on the hood.
External Symmetry is comprised of foundational attributes like table and culet alignment, uniform shape outline, and facet pointing. Here you see minor symmetry faults that would prevent a diamond from being an 8X.
Optical scanning technology measures each facet and angle to produce an accurate, to-scale diagram of every diamond. These narrow proportion tolerances were selected because they represent the intersection at which the perfect combination of brilliance, fire, and scintillation is achieved.
Rounding – one question asked in the thread for this webinar was what rounding we use. We intend to make a few enhancements to our certificate in January. Here are the new values and associated rounding rules. One is to change the rounding to 0.1 percent or degrees across the board. Another enhancement we are considering is publishing the deviations in angles, and possibly adding additional data sets, or even native helium files on the site for further analysis by interested shoppers.
Another question concerned painting and digging. We were asked what tolerances we use, and can it be seen in our images. Here are the tolerances we use for RB 8X.
And here you see examples of pavilion digging ranging from 0.33 degrees to 0.92 degrees. You will see the edges of the stone start to go from red to black (when you see our symmetry dome, this will make even more sense).
This is an example of crown digging, where you start to see increased leakage around the stars. You’ll also see an example where average pavilion digging doesn’t tell the whole story, as the max is 4.91, visible at 3 o’clock in the stone.
Here you see the GCAL 8X, GIA 3X and AGS triple zero proportions side by side, and you will see the significant differences in the standards. One quick note…finding the precise tolerances that AGS and GIA use is actually quite difficult, so these parameters are based on data from their websites, and from actual reports that received triple ex and triple 0 grades. And while the GIA and AGS systems allow only specific combinations within these ranges, you will note how vastly different they are from 8X, and how wide they both are. One easy way to think about this chart – every GCAL 8X Certified diamond would be guaranteed to make Triple Ex or Triple Zero. but the reverse is not true.
Brilliance is the overall return of white light to the viewer. It is measured by GCAL proprietary technology to the thousandth decimal place, and is represented in the images you see here. This is a leakage analysis visible in the white areas in the top right image, and inverse in the brilliance image on the bottom right. This is also what you see on the GCAL Certificate.
Here you see an example of a well proportioned stone, contrasted with a deep stone with a large table. You can note the obvious differences in visual appearance in the photographs, and in the brilliance images.
Since I know many of you understand and appreciate the Ideal Scope image, I wanted to show you actual images of the same diamond – GCAL Optical Brilliance and Ideal Scope. In our image, blue is leakage, grey weaker light return, white is light return, but not visible is the obstructed light. In the Ideal Scope image, white is leakage, pink weaker light return, red is light return, and black is obstructed light. The importance of this is if you have a GCAL Cert, you can derive the same information about leakage as if you had an Ideal Scope image.
Fire results when white light travels through a diamond and is dispersed into its rainbow of spectral colors. These flashes of color contribute to sparkle and are best viewed as the diamond moves. Here you see two diamonds, one with Good Fire, and an 8X with Excellent Fire.
Each fire video is composed of 200 frames that are processed to analyze the quantity and size of colored light return, as the diamond is tipped and tilted.
Here are examples of Ovals with Fair to Excellent fire.
Scintillation is the flashes of light, or sparkle, produced when light is reflected from a diamond as it moves. This video shows the light returned from a single beam of light when your diamond is rotated in nine positions.
Here is a short video showing how we measure scintillation from our Gemprint instrument.
Gemprint records a unique optical fingerprint of each diamond that we certify.
Gemprint is used across the supply chain for identification and recovery.
This is another illustration of the diamond as it is tipped and tilted into 9 different positions.
Here is an example of Excellent Scintillation being compared to a Good Scintillation.
Scintillation images are all captured and evaluated in full on a square background, and then cropped to the shape outline on the certificate. The full scan can be seen on our website.
Symmetry is seen everywhere in our daily life. It is aesthetically pleasing, and plays an even more important role when it comes to diamond cutting.
Optical Symmetry is visualized in these photographs taken in a 5-angle reflector. The evenness of the pattern illustrates the precision and uniformity of facet shape and alignment. Here you see the angles at which we capture these images.
Our 5-angle reflector was developed by the Diamond Profile Laboratory in 1997. GCAL acquired all intellectual property of the company in 2004. Al Gilbertson, who was a consultant to Diamond Profile Lab, trademarked his Gilbertson Scope in 2001, which was then assigned to 8 Star, and ultimately sold to AGS, which became the ASET, introduced in 2005. All this is to say many of these multi-colored scopes are derivatives of the IP that GCAL acquired.
Here are actual images of the GCAL Symmetry Scope and a backlit ASET Scope. You will see leakage in the same points – our red and green are a similar angle to their red, and our blue is equivalent to their green. You can see both minor and major facets in our analysis, and the definition and contrast of facets appear to be more clearly defined in the GCAL dome.
One question that comes up often is how and why external symmetry and optical symmetry could be graded differently for the same stone. And it’s a great question, with a semi simple answer. Every single angle, relative angle, facet shape and facet size contribute to the diamond’s optical symmetry. With external symmetry, sometimes these slight differences are imperceptible. For example, how many of you could discern a 1° variance in pavilion half angles 5 and 16? Or a 2% difference in lower girdle facet lengths? I’d say not many. But this variation could have a dramatic impact on the optical symmetry of the stone, as light is reflected and refracted throughout the stone. So this stone you see on the screen is a great example of this deviation. This stone was graded Triple Excellent, but only has a Good optical symmetry grade.
On the screen, you will see 8 Optical Symmetry images. All of these diamonds were graded Triple EX, but only 1 has Excellent optical symmetry. If you thought H had the Excellent optical symmetry, you are correct.
On the screen, you will see 3 stones graded triple zero by AGS. But only one would be considered Excellent optical symmetry by GCAL. As you can see, there’s quite a wide variance between these 3 stones, and while the mostly easily observed attributes on these 3 images is optical symmetry, AGS doesn’t actually grade optical symmetry. So this explains how these 3 stones, with different levels of optical symmetry, could all still achieve the highest grade of triple zero. And If you thought C was the one with excellent optical symmetry, you would be correct.
The final X for round brilliants, is Hearts & Arrows, which is visualized when round brilliant cut diamonds are viewed in specific lighting conditions. Each pattern is the result of superior facet placement and exact alignment. Again, all of these diamonds were graded Triple EX, but only 1 has what GCAL would consider an excellent H&A pattern. If you thought D had excellent H&A, you would be correct.

GUEST SPEAKER: ANGELO PALMIERI, GCAL COO & PARTNER: Angelo will focus on what consumers need to know about diamond cut, and why it is so very important in making that ultimate purchase. He’ll walk you thru each of the 8 “Excellents” of 8X, explaining how the tight proportions were determined, and what you and your customers need to know about diamond cut grading. 

HOST: DAVE ATLAS, PRICESCOPE DIAMOND CONCIERGE LEAD: David has gained a lifetime of experience in many aspects of jewelry sales, estates, design, manufacturing and appraising. David currently holds the titles of Certified Senior Member, Natl Assn of Jewelry Appraisers; Graduate Gemologist, GIA; Associate Director and Chairman of Ethical Issues, NAJA.

ABOUT PRICESCOPE: PriceScope is the largest online diamond and jewelry community in the world, with over 120,000 registered members and more than 260,000 forum threads.