Diamond Cut: The Basics – Understanding Technology
In order to understand the different measurements, tests, and evaluations that diamonds are put through, and what the results of these test mean to the diamonds visual performance, it is necessary to first have a solid grasp on the technologies and techniques used to gather this data.
There are many different tools that are used by gemologists and diamond graders to determine facts about a diamond’s properties. This section is going focus mostly on the more complex and less understood tools, and is also going to focus mostly on tools used to determine cut and light performance.
The Sarin machine is the most popular device in a small group of machines called “non-contact measuring devices”. These tools are, in essence, scanners that scan the outside surface of the diamond and measure all the flat surfaces of the stone. They do this by taking many 2 dimensional images of the diamond’s silhouette, and from these images, constructing a 3 dimensional model of the diamond, complete with measurements, that is able to be manipulated by the gemologist. Basically the Sarin is able to reconstruct the diamond in a virtual world with extreme accuracy.
This is extremely useful for gaining measurements on the diamond, examining the cut of the diamond, determining angles, and more. In addition, the computer software is able to simulate light sources, thereby allowing the gemologist to subject the diamond model to different types of light, at different strengths and from different (single or multiple) angles, and more. This allows the diamond to be analyzed scientifically in a completely virtual realm with astonishing accuracy. The data gained from this analysis is very useful in determining the quality of the diamond’s cut, and hence, its ability to reflect light.
Similar scanners to the Sarin are the Helium Scanner and the OGI Scanner. At Emma Parker & Co. we use the Sarin.
A simple yet critical set of tools that is used to study and critique a diamond’s cut and light performance are the “reflector devices”; the most well known of these devices is called the Ideal Scope.
The premise of these tools is quite simple; they show the light that is being reflected by the diamond in a form that is visible to the human eye. This allows a person to observe “light return” vs. “light leakage” in a diamond easily.
Having read the Emma Parker & Co. Diamond Tutorial, you should have a solid grasp of the function of the Ideal scope and other devices such as the AGSL ASET reflector. If you have not yet read the Emma Parker & Co. Diamond Tutorial, please stop here and read that in its entirety before continuing on, as it will be necessary in order to understand the upcoming chapters of this tutorial.
The DiamCalc Software is a wonderful program that is designed to take the diamond models that are generated by a “non-contact measuring device” and put them into a visible model that can be manipulated in a plethora of conditions, angles, lighting, and so on.
It can even take the diamond models and simulate them under “reflector devices” such as the Ideal Scope, ASET, Firescope, and more. This program is able to “skin” the diamond, if you will, with a visual appearance that is very similar to the real life diamond.
One of the strongest features of this program is that it allows the user to enter different parameters for the diamond. For example, if we know that a diamond with proportion set 1 looks good, but we want to see what would happen if the table was a different size, we can change the table in the program, and see the effects of this change on the diamond, both visually, and through a reflector device. This is an incredibly powerful tool for research and demonstration.
The BrillianceScope was designed to measure the light return/optical performance of a diamond in direct light. The technology is actually a very simple and logical design.
Have a look at Figure 3.1
Copyright Emma Parker & Co. 2008
This is a basic diagram of the inner workings of the GEMEX BrillianceScope. The diamond rests on a circular piece of glass. The cover over the diamond is then closed, creating a completely white environment surrounding the diamond. (See Figure 3.2
Courtesy of GEMEX
Light, generated by a fiber-optic ring light is then projected up, through an opening in the white half-sphere, through the glass, into the top of the diamond, as illustrated in Figure 3.1.
The light moves to 5 specific sets of three individual points, stopping briefly at each of the 15 points. For each set of points, a camera, at the bottom of the machine, aiming up through the center of the ring light, triple exposes an image of the diamond, one picture at each point in the set, “laid” one on top of the other, as it were.
Once these images are captured and stored, the software breaks down each image on a pixel by pixel basis, and looks at three distinct items.
1. The amount of White Light being reflected by the stone. This will account for brightness or brilliance to the viewer’s naked eye.
2. The amount of Colored Light being reflected by the stone. This will account for the fire or rainbow colored light to the viewer’s naked eye.
3. The “movement” of light within the diamond, otherwise called Scintillation. This will be seen as sparkle to the viewer’s naked eye.
These results are then compiled, and compared against a controlled database of diamonds that have been tested on the machine, and the results of these tests form the basis for the “grading by comparison” system used by the GEMEX software. The result is a report like the one pictured below.
Courtesy of GEMEX.
The results of the GEMEX report, displayed above in Figure 3.3, are heavily curved; i.e. meaning that from the bottom of the chart to the middle of the “HIGH” grade encompasses up to the 85th percentile of all diamonds tested, while grades from the middle of the “HIGH” mark to the end of the scale at “VERY HIGH” comprise the 86th – 100th percentile of all diamonds tested.
The GEMEX is an interesting tool, and is useful to a point for gaining a perception of how a diamond will perform in direct lighting conditions, such as direct sunlight, direct spotlighting, etc.
The GEMEX is limited by the fact that its results only apply to direct lighting, and that its “grading by comparison” system is a totally subjective grading system which, by its nature, will always be subject to any influences that affected the block of results from the control group upon which the entire basis of the grading schematic rests.
Another drawback to the GEMEX is that results can be manipulated slightly by a crafty user. Something as simple as placing a finger print smudge on the top of the diamond can cause a much higher rating on the White Light performance than the stone would have if it were totally clean. Meticulous cleaning of the diamond and the glass is absolutely necessary to ensure a proper scan. GEMEX inspects each scan before a report is issued and will reject reports that show excessive dirt or smudging, however the ease with which results can be manipulated remains a draw back in our opinion.
Having an enormous amount of experience with the GEMEX BrillianceScope, both as a selling tool and as an analysis tool, I do believe that the technology is by enlarge sound, and the results valid. I have also found that consumers place far too much importance on the report, and often find themselves crippled with “analysis paralysis” and the fear that they should be waiting for a diamond that scores “the perfect 10” on the BrillianceScope, while letting world class diamonds go by on a technicality from a subjective, computerized, “grading by comparison” system. This is foolish and should be avoided. It is important to consider all aspects of a diamonds performance when purchasing a stone. To do this, one must consider a full body of analysis, of which the BrillianceScope is an informative, albeit non-essential piece.
Courtesy of ISEE2 Diamonds
The ISEE2 machine is another technology that measures a diamonds Brilliance, Fire, Scintillation, and Symmetry in a controlled light setting using mainly diffused light. The inventor of the ISEE2 states that the machine subjects diamonds to 48 different lighting conditions. The ISEE2 takes 15 images a second, and analyzes these images, breaking them down to analyze White Light, Colored Light, Light Movement (Scintillation), and Optical Symmetry (the pattern cut into the stone, in this case the machine is looking for the hearts and arrows pattern that is most commonly displayed in a properly cut 57 facet, traditional pattern round diamond).
Having extensively used the ISEE2 machine for both the sale and analysis of diamonds, I can say that the results of the ISEE2 are consistent with other technologies, and are valid for consideration, provided that they are not overly weighted by a consumer in making their decision.
As with the BrillianceScope, the rating system used by the software program is proprietary and unknown to anyone other than the developer. As with the BrillianceScope, this would not normally be a reason for concern, as the results have been shown to coincide with scientifically established measurements for “ideal light performance”, save for one critical piece of information; the ISEE2 machine was developed by the manufacturer of ISEE2 Diamonds specifically for the sale and marketing of their own ISEE2 Branded Diamond, which is a 57 facet Ideal Cut Hearts and Arrows Diamond.
This fact does not invalidate the ISEE2 as a technology, nor yield its results as void, it merely casts a rebuttable shadow of doubt on a technology that has tested positively in private lab tests with both ISEE2 Diamonds and non-ISEE2 diamonds. The problem lies within the subjective “grading by comparison” standard that is employed by the software, which is proprietary, and therefore not discernable by consumers. So far, independent testing, including my own extensive use of the ISEE2 seems to show that the grading put forth by this technology is consistent and relatively accurate when compared to the current positions, in regards to cut, of the major gemological laboratories, such as GIA and AGS.
As with the Brilliance Scope, the ISEE2 is an interesting, albeit non-essential source of information that can be considered when purchasing a diamond. The most prominent danger posed by this technology is the overemphasis that is often placed by the consumer on the importance of its results.
GIA Diamond Dock
Courtesy of GIA
The GIA Diamond Dock is a lighting source that is used to evaluate diamonds. (Figure 3.5) This lighting environment is intended to simulate true “daylight” as closely as possible. Using a combination of diffused fluorescent lighting and L.E.D. direct lighting, it is able to simulate daylight fairly accurately.
This is very useful for observation, photography, and “naked eye” light performance analysis of a diamond.
The Diamond Dock also doubles as a color grading environment.
TECHNOLOGIES THAT DO NOT PRETAIN TO “CUT GRADE ANALYSIS”
Traditional Jeweler’s Triplet Loupe
Courtesy of Kassoy.com
A traditional jewelers “triplet” loupe is a simple tool that you will find in almost any good jewelry store. This is a simple, hand-held magnifying lens that allows a viewer to inspect the diamond under magnification fairly easily and in almost any location and situation. The standard magnification for these loupes is 10x, however different loupes are available for 20x and 30x as well.
This particular kind of loupe is referred to as a “triplet” because the magnifier is actually made up of three different lenses in order to provide the highest clarity to the viewer.
At first, using a loupe can be tricky, however with a little bit of practice, it is possible to gather a vast amount of information about a diamond simply by taking a good, long look at it through a loupe.
High Power Microscope with High-Definition Camera
Courtesy of Kassoy.com
A good source of high magnification is critical to the proper analysis of any diamond. While observing a diamond through a 10x triplet loupe is good, having the ability to zoom in to 50x or 60x magnification allows a jeweler to learn much more about a diamond and its imperfections, as well as its cut. In addition, having the ability to share this information with a customer is vital to ensuring that the customer feels confident in the diamond they are looking to purchase.
At Emma Parker & Co., we use the microscope pictured above. It is a 50x magnification microscope, with glass lenses produced by the company Leica, a leader in the optical glass industry. The microscope also has a high definition camera mounted on it, through which images of inclusions can be taken, and live video of the magnified diamond can be streamed.
The pictures taken by this microscope allow customers to see, in remarkable detail, the characteristics of the diamond magnified. See examples below…
The red arrows point to the “grading inclusions” in the diamond. These are the imperfections that contributed towards the diamonds clarity grade, as given by the grading laboratory, such as GIA or AGS.
At Emma Parker & Co., we point out these inclusions with red arrows in a picture taken under the microscope so our customers can easily locate the incusions in their diamonds.
Courtesy of Kassoy.com
In today’s advanced technological market, advanced and accurate tools have emerged for determining the color of a diamond. The tools, called “colorimeters” have advanced to such a point that they are quite accurate and sophisticated. These are fantastically costly machines, and are not used by everyone in the industry.
Like many of our fellow colleagues, we here at Emma Parker & Co. prefer the old fashion way of color grading, the way that GIA and AGS still use to grade diamonds, a white tray, a color grading light, and set of master stones.
We feel that some things are better left to the human eye and trained observation.