Diamond Analytics - Understanding Diamond Light Performance & Craftsmanship

Rough diamond crystals are remarkably unremarkable. In their uncut state they possess no brilliance, no fire, and are anything but scintillating! Without the craftsmanship of man, diamonds look no different than a piece of common quartz or a shard of broken glass. But even the earliest diamond cutters, who were able to put just a few rudimentary facets on a diamond crystal, were able to begin to unlock the extraordinary beauty of the ‘gem of gems’.

Diamond cutting today is very sophisticated and manufacturers are able to fully maximize the phenomenal optical qualities that lie within a gem diamond crystal. Modern diamond cutting employs precision tools and technologies that enable extremely fine adjustments to the angles and alignments of the diamond’s facets. This level of control allows the diamond cutter to make decisions that impact both light performance and the yield of finished diamond from the rough. He must always be cognizant of both, along with current market values, in order to successfully ply his craft.

Modern analytic tools give cutters, merchants, and consumers alike, the ability to assess diamond cut quality and light performance in ways never before possible. From simple reflector tools like Ideal Scope, H&A viewer, and ASET, to the more sophisticated ray tracing software programs such as AGS Light Performance and DiamCalc. These programs are capable of making tens of thousands of precise calculations and mapping the behavior of light in 3D models generated by highly accurate scanning devices such as those manufactured by Sarine. And web-based tools such as GIA Facetware and Holloway Cut Advisor can be helpful to shoppers online.

One of the key developments in advanced diamond analysis was the coming of age of precision non-contact measuring devices such as those manufactured by Sarine Technologies. Their DiaScan instrument makes a 360 degree scan of the diamond measuring all the facets in fine detail. It generates a variety of reports and produces a 3D model that can be used in sophisticated ray tracing software programs such as AGS Light Performance and DiamCalc. Sarine is capable of measuring a diamond more thoroughly, more accurately and much more quickly than a gemologist ever could using manual techniques.

The graphical representation of the light performance cut grading system developed by the American Gem Society Laboratories (AGSL) is the ASET. This powerful analytical tool shows how the diamond is handling light in a comprehensive and easy to understand color-coded way. It not only shows light return, light leakage, and structured contrast, but also reveals information about the quality of light being returned to the eye.

The Ideal Scope is a simple reflector tool that reveals easy to understand information about light return, light leakage and contrast patterns. Red is light return, white or grey is leakage, and black represents structured contrast. It provides a subset of the information that ASET reveals, and is a tool more commonly found in the trade. Like ASET, it is available in a small portable and consumer-friendly tool as well as the trade versions designed to capture images.

The Hearts and Arrows Viewer is another of the simple yet powerful reflector devices available to the consumer. It provides visual information about the optical precision of the diamond. Only when the diamond has been crafted in such a way that all facets are aligned properly in three dimensional space will the diamond exhibit a crisp pattern of eight arrows through the table and eight hearts through the pavilion. Ideal proportions combined with hearts and arrows precision result in optimal performance. The benefits of Hearts and Arrows precision extend well beyond the intriguing patterns.

The Holloway Cut Advisor (HCA) tool is an easy to use online evaluation program that provides some useful information about diamond proportions. By inputting a few basic parameters it will generate an estimate of cut quality. Because it is not a direct assessment tool and does not gather any information about many of the key facets that determine actual light performance, the HCA is only valuable as a filtering tool to exclude problematic proportion sets. The significant limitations of the HCA render it of negligible value when the diamond is accompanied by an AGSL report or light performance images such as ASET or Ideal-Scope.

There are a few very sophisticated software programs dedicated to studying and grading diamond light performance. DiamCalc from Octonus Software is one of the most robust. Full of features for modeling diamonds in a wide range of ways, DiamCalc is capable of taking a scan from a Sarine or Helium device (the Octonus device similar to Sarine), and rendering many types of computer generated images including ASET, hearts and arrows, and even photo realistic video. DiamCalc software is used by diamond manufacturers, dealers and researchers all over the world.

Whether you are evaluating a diamond online or one at the local jeweler, light performance imaging gives you critical information about the diamond that you may not be able to discern by visual inspection alone. Diagnostic tools like ASET, Ideal Scope and Hearts and Arrows viewer reveal aspects of performance such as light leakage, optical symmetry faults, contrast issues, and other problems. High Definition video enables a magnified inspection and the opportunity to see dynamic aspects of performance such as scintillation and fire. By evaluating diamond images in conjunction with a lab report, it is possible to gain a comprehensive understanding of the critical factors that determine a diamond’s beauty.

Approximately 25-30% of diamonds exhibit a property known as fluorescence. Certain wavelengths of light (primarily ultraviolet) cause the diamond to emit light as long as the source of these wavelengths is present. As a result the diamond glows in varying colors (usually blue) and in different strengths. Fluorescence is primarily an identification characteristic, but can have impacts on appearance and value. When considering a diamond with this characteristic it is wise to fully understand its implications.

The popularity over the last several years of princess cut diamonds has put huge numbers of these diamonds on the market, most of which do not possess top quality light performance. This is in part the result of the role laboratory reports play in the marketing of diamonds. Because GIA, the most well-known lab in the world, has elected not to put overall cut grade on reports for princess cuts (or any non-round shape), cutters are not bound by strict light performance considerations. They are able to retain more finished weight with princess cuts which are not cut to ideal proportions, thereby maximizing yield and profitability. Princess cuts with GIA reports showing Excellent/Excellent in polish and symmetry are marketed successfully as top cut quality, even though actual light performance may in fact be poor. This is likely to continue until either GIA implements cut grading for princess cuts, or until more consumers become educated about the issue.

Light performance grading reports on fancy shapes are available through AGSL and shoppers looking for princess cuts with the most fire and brilliance should seek out diamonds graded by the AGS Laboratories as Ideal. (To learn more see our page on princess cut grading.)

Diamond cutting involves several distinct phases, each one critical to the quality and value of the finished product. The planning of the cut is perhaps the most important step and involves not only a study of the shape and quality of the rough, but an analysis of the market potential for specific shapes, qualities and sizes. A given piece of rough could be cut in many different ways. Calculating the most profitable approach is a key step from which everything else stems.

With greater understanding of the benefits of top cut quality and craftsmanship, the market for ideal diamonds is growing rapidly. The popularity of Hearts and Arrows diamonds is an outgrowth of the new cutting capabilities that can result in perfect 3-dimensional symmetry of the finished diamond, creating the H&A patterning visible under special viewers. The growing availability of diamond imaging diagnostics provides shoppers with a wealth of information about the light handling properties of the diamonds they are considering for purchase.

Diamonds that are intended to become the “best of the best” in terms of cut quality, like the A CUT ABOVE® Super Ideal (in both H&A round and princess cut), require much more time and attention. Minute differences in measurements, angles, and facet alignments must be resolved. More of the diamond rough is cut away in the process as well, yielding a smaller diamond but one with optimal light performance. The result is a premium quality diamond exhibiting the ultimate optical beauty that space age technology and modern craftsmanship can produce.

While mined diamonds are certainly rare, and they are the hardest known natural substance, it is their propensity for stunning optical beauty that really makes them desirable. This begs the question of why diamonds aren’t always cut to maximize light performance. In the information age more people are asking that question and more manufacturers are stepping up their game to fill the growing demand for precision cut diamonds.