GIA: Research: Article Archive

February 25, 2003 Computer Modeling Part 2: A Closer Look at Metrics There are many phenomena in the world that we would like to understand better. Complicated interactions, such as weather patterns or economic fluctuations, are difficult to study not only because of their many variables, but also because it is often impossible to conduct experiments in which we control enough of the variables to reveal the underlying causes of these interactions. Understanding the effects of various proportion parameters on the appearance of a polished diamond is a similar situation: A thorough research study requires the ability to test hundreds of thousands of proportion combinations under many lighting conditions and observer positions.
September 27, 2002 How Science Works: Understanding the Scientific Method (Summary) In our previous articles in GIA On Diamond Cut, we examined a variety of information that is essential for understanding issues related to polished diamond appearance. For the most part, this information would come as little surprise to those in the scientific community who are familiar with diamonds; it forms the basis of our current knowledge of diamond appearance.
September 27, 2002 How Science Works: Understanding the Scientific Method In our previous articles in GIA On Diamond Cut, we examined a variety of information that is essential for understanding issues related to polished diamond appearance. For the most part, this information would come as little surprise to those in the scientific community who are familiar with diamonds; it forms the basis of our current knowledge of diamond appearance.
August 30, 2002 The GIA Diamond Proportion Module: Illustrating How Changes in Individual Proportions Affect the Appearance of a Round Brilliant Cut Diamond In several previous articles of the GIA On Diamond Cut series, we have emphasized the importance of considering every proportion when examining the overall appearance of a round brilliant cut (RBC) diamond. We believe that the traditional approach needs to be updated to include other proportions that can significantly alter the appearance of a diamond and the amount of light it will return.
November 30, 2001 Diamond Appearance: The Components of a Computer Model Authors: Barak Green, Mary Johnson, Ilene Reinitz, and James Shigley There has been a tremendous increase in the application of computer modeling to complicated, real-world problems in the last few decades. As the processing power of computers has grown, so has our ability to mimic, and experiment with, a wide variety of real-life situations. These include weather patterns, financial markets, and biological processes such as cell growth or the spread of viruses in populations. Computer modeling allows researchers to experiment in areas, and with materials, that normally would be impossible to explore. This has been especially true in our research on diamond cut.
November 16, 2001 The Visual Presentation of Information: Part 2 Informational graphics are useful tools for the presentation and analysis of information. Not only do such graphics allow us to see patterns in the data that might otherwise remain hidden, but they also permit the presentation of a lot of information in a relatively small space. Ultimately, well-designed informational graphics promote the understanding of extremely complex or potentially confusing information.
October 26, 2001 The Visual Presentation of Information: Part 1 There are many ways to present information visually. Popular media (e.g., newspapers, magazines, and television news shows) use a variety of formats to present information to their readership and viewers. For most of us, maps, graphs, and pie charts are familiar sights. We are used to seeing weather reporters use maps and tables to show us the weekly forecast, or watching business analysts use graphs to illustrate the movement of the stock market. Many of us are also familiar with topographic maps that use colors to show the elevations of mountains, or the depths of oceans. All of these formats are different methods of conveying information, and we have used many of them to present and analyze our research on diamond cut.
September 28, 2001 The Optics of a Dirty Diamond Many circumstances contribute to the beauty of a diamond. In previous GIA on Diamond Cut articles, we have discussed some factors that help to determine the appearance of a polished diamond. Most of these factors are optical properties of the diamond itself. These include: the laws of reflection and refraction, critical angle, dispersion, polarization, and the three-dimensional shape of a diamond.
September 14, 2001 What did Marcel Tolkowsky Really Say? The gemological world has its own unique culture. It has its own histories and discoveries, myths and wonders, language, and legendary personalities. Perhaps one of the most famous names in the gemological world, and certainly in that portion concerned with diamonds, is Marcel Tolkowsky. In the years since he outlined his idea of optimum diamond proportions in 1919, his name has been synonymous with ";well-cut"; diamonds. Even a casual glance through internet diamond retail sites reveals numerous (sometimes reverential) mentions of his name. Though many people mention Tolkowsky and his book Diamond Design, few have had the chance to read this treatise, and fewer still have attempted an analysis of its strengths and weaknesses. Who was Marcel Tolkowsky?
August 17, 2001 The Importance of Three-Dimensionality A polished diamond owes its beauty to many interrelated factors. As we have seen in the previous articles, several interdependent relationships affect light's behavior in a polished diamond, and thus can affect that diamond's appearance. The properties that we discussed in the articles on diamond optics (Diamond Optics Part 1; Part 2; and Part 3) help us predict some of these appearance aspects (e.g., brilliance or fire); however, we also need to consider a fashioned round brilliant cut (RBC) diamond as an object that has three dimensions$#150;height, width, and depth.
August 03, 2001 Diamond Optics Part 3: The Effects of Polarization States on Light Behavior To further understand light behavior in a round brilliant cut (RBC) diamond, and how cut proportions might affect this behavior, it is necessary to continue our discussion of diamond optics. Along with reflection, refraction, and dispersion, the polarization state of each ray of light affects that ray's behavior in a polished diamond. This article builds on the optical concepts and definitions outlined in "Diamond Optics Part 1" and "Diamond Optics Part 2". You might want to review those two articles before reading this one.
July 20, 2001 Diamond Optics Part 2: Light Dispersion, Color Wavelengths and Fire To further understand the effects that cut proportions have on the appearance of a round brilliant cut (RBC) diamond, we must continue our review of diamond optics. In this article we expand our exploration of light movement to include the optically dispersive nature of diamonds, the different wavelengths (colors) contained in white light, and the various causes of the visual appearance aspect of "fire". This article builds on the concepts and definitions outlined in Diamond Optics Part 1. (You may wish to review that article before reading this one.)
July 06, 2001 Diamond Optics Part 1: Reflection, Refraction and Critical Angle Polished diamonds rely on light for their beauty. Light brings together the inherent properties of diamond, the optical effects created by faceting, and the observer's ability to appreciate the gemstone. To understand the effects that cut proportions have on the appearance of round brilliant cut diamonds, it is important to begin with a general review of light and optics. This is the first of three articles in this diamond cut series that will briefly explore these topics as they relate to a polished diamond's appearance.
June 22, 2001 GIA and Its History with Cut GIA's study of diamond cut proportions has a long history—longer, in some ways, than the history of GIA itself, since one could say that poor cutting proportions helped motivate Robert M. Shipley to found GIA. In the mid-1920s Shipley, a successful jeweler, met with one of his wealthy clients who had just returned from the diamond cutting centers of Europe. This client informed him that his knowledge of diamonds was incomplete. Although Shipley knew as much about diamonds as most American jewelers at the time, he felt embarrassed to discover that he had sold many diamonds with apparently "poor makes"—that is, diamonds that were cut badly.
June 08, 2001 Cut-The Least Understood "C" A good place to start examining the importance and evaluation of cut in polished diamonds is with the "Four Cs". This phrase refers to a diamond's Carat weight, Clarity, Color, and Cut (listed from simplest to most complicated to understand). Although all of these value factors have been around as long as diamonds have been polished, grouping them together into a descriptive concept such as the Four Cs was the idea of GIA founder Robert M. Shipley for De Beers, and was intended as an educational tool for consumers and jewelers. It was their hope that by organizing a diamond's value factors into simple categories, individuals would be better able to understand the variables that are most important in the evaluation of a polished diamond.