GIA Also Announces a new cut grading system.

The article below is a very long and boring read. Typical of something from the GIA. The GIA (Gemological Institute of America was thie first to come out with a standardized way of grading diamonds. Not only by cut proportions, but by the color, and the clarity. They have a great tutorial on their site that teaches the scientific aspects of these three of the four C's. Don't worry, it's meant for the public, not for a scientist. They did a decent job of explaining in a fairly short and simple way all of the four C's. (in case you were wondering what the fourth C is- Carat weight.) You can see this tutorial at their site: http://www.gia.edu/howtobuydiamond/menu.htm .

For those of you who would rather spend your time not reading through this, here's what it boils down to:

Over the last 10-15 years many jewelers and diamond cutters have argued about what proportions of a diamonds cut should be to attain the best sparkle. With new technology abounding there has been a couple of companies develop machines that will actually measure how much sparkle a diamond really has, where before you were only guessing based on the cut. When we say "the cut" we mean how each and every facet (face) on the diamond touches the facets around it, how big each facet is, what shape it is (most are kite shaped) and how smoothly it was polished. 

Some retailers have machines on their showroom floor where they will place the diamond you are looking at into the machine and it will grade the diamonds sparkle factor.  This is probably one the first truly use full machines to the potential diamond buyer. 

So, being able to actually measure how much each diamond sparkles is a great tool, that's what people look for when she waives her finger around to show her new ring. You don't hear comments about the geometry or what shade of yellow it is. They talk about how "fiery" or "sparkly" it is.

 

GIA Outlines Basis for New Cut Grading System
	By GIA Research	Posted: 11/30/2004 9:50 AM
	The following is a press release from the Gemological Institute of America (GIA). It was received by Rapaport News on Tuesday November 30. GIA on Diamond Cut: Latest Gems & Gemology Article Outlines Basis for New Cut Grading System By GIA Research Carlsbad, Calif. – Nov. 18, 2004 – Issues regarding diamond cut, particularly the relationship between a round brilliant’s proportions and its appearance, have captured the attention of many in our industry during the last decade. Although some believe that only certain narrow proportion parameters yield the best appearance, cut has remained the least understood element of diamond quality. During this time, the Gemological Institute of America (GIA) has worked to determine what it takes to produce an attractive, lively diamond. The Institute’s 15 year research project has examined the intricate and complex relationships among the various factors that lead to a diamond’s face-up appearance and identified the aspects that are essential to good cut quality. The article in the Fall 2004 issue of Gems & Gemology, “A Foundation for Grading the Overall Cut Quality of Round Brilliant Cut Diamonds” by T. M. Moses et al., ties the various elements of GIA’s study together to outline the scientific basis for a diamond cut grading system. The key results of this study bring to fruition the previous GIA reports on brilliance (in the Fall 1998 Gems & Gemology) and fire (in the Fall 2001 Gems & Gemology). Some of the main findings from GIA’s research discussed in the new article are: • Proportions need to be considered in an interrelated manner. The combination of proportions is more important than any individual proportion value. • Attractive diamonds can be manufactured in a wider range of proportions than would be suggested by historical practice or traditional trade perception. • The quantity and quality of brightness (as brilliance is now called) and fire are only part of overall diamond appearance. The pattern of bright and dark areas within a diamond (the basis of scintillation) must be considered as well. • A thorough cut grading system needs to consider the design of a polished diamond (as evidenced by its weight ratio and durability) and its craftsmanship (as evidenced by its polish and symmetry). • Viewing environment plays an important role in diamond appearance: to be attractive, a diamond should look good in realistic environments. • Personal and international market preferences should be accounted for. Diamonds with different appearances can be found within each cut grade, so individuals need to look at the diamond itself, not just its grade, to choose the one they like best. Results From Computer Modeling and Observation Tests The GIA researchers based their findings on the results of the two main parts of the research project: computer modeling to predict which sets of proportions would yield the best results under specific lighting conditions; and extensive visual preference tests conducted with a wide variety of trade and non-trade observers to determine the ability to consistently discern face-up appearance aspects (brightness, fire, and scintillation) and the importance of other cut quality components (such as durability and finish). The results of the preliminary computer modeling for brilliance and fire were reported in Gems & Gemology. Comparison of those results to observations of actual diamonds in similar conditions allowed the researchers to refine these metrics. Further observation tests evaluating overall appearance, made by representatives from all levels of the diamond trade in controlled viewing environments, also confirmed that those two aspects alone were insufficient to predict the appearance of many diamonds. “Our initial observation tests revealed that, as we expected, our best brightness and fire metrics were able to predict specific observation results (i.e., brightness and fire), but they were not adequate to predict and evaluate a diamond’s overall cut appearance and quality,” wrote Moses and his colleagues. These tests included over 70,000 observations of nearly 2,300 diamonds by more than 300 individuals. In these sessions, observers indicated their preferences in groups of two or more diamonds. The results yielded newly expanded definitions of brilliance—now called brightness by GIA—and scintillation. Brightness is the appearance of white light seen when viewing a diamond face-up (this includes the effects of direct reflections—or glare). The researchers preferred to use the term brightness (over brilliance) because many individuals in the trade and general public associate brilliance with other appearance factors (such as contrast). In the new article, scintillation is defined as: (1) the appearance of spots of flashing light seen as the diamond, observer or light source moves (sparkle), and (2) the relative size, arrangement and contrast of bright and dark areas that result from internal and external reflections seen in a diamond when it is viewed face-up, while that diamond is still or moving (pattern). Typical examples of pattern-related scintillation include fisheyes, dark upper girdle facets, and dark centers. The viewing environment (whether in a dealer’s office, retail store, or the many places in which a diamond is worn by a consumer) was found to play a significant role in how a diamond looks. To facilitate consistent observations of cut appearance, the researchers developed a standard lighting environment, consisting of a neutral grey box lit by diffuse lighting (for brightness) and directed “spot” lighting (for fire). The research demonstrated that observations made in this environment yielded the same relative ordering of a set of test diamonds as the observations made in typical trade environments. The researchers also investigated how other quality factors—such as body color, clarity, and fluorescence—affected the relationship between a diamond’s proportions and its appearance. Body color was found to have some effect on the appearance of brightness, and some clarity characteristics were found to affect the appearance of fire, but observers demonstrated a strong, consistent ability to disregard these effects when judging overall diamond appearance. In addition, specific aspects of design (weight ratio and durability) and craftsmanship factors (polish and symmetry) were found to affect overall cut quality. GIA’s diamond cut grading system, when introduced, will consist of five grades for overall cut quality. These grades will consider seven separate components in their assessments: brightness, fire, scintillation, weight ratio, durability, polish and symmetry. To arrive at the final overall grade, each component is individually assessed, and the lowest result from any of the seven components determines the final overall cut grade. ---Benefits of GIA Grading System The result of this research is a comprehensive predictive system, based on computer modeling and human observations, which has the flexibility to accommodate most personal and international preferences. The new GIA diamond cut grading system will benefit consumers and the trade by accommodating a larger range of proportion sets that provide pleasing, well-cut diamonds. Consumers will feel more secure in using cut quality as a factor when making buying decisions (much like they currently use the other three Cs of color, clarity and carat weight) with the new GIA cut grade. Retailers will benefit from GIA’s new diamond cut grading system. In addition to the availability of a broader range of diamond proportions that are considered well-cut, they will have new opportunities (and a system that supports those opportunities) to educate their customers on the Fourth C. Manufacturers also will benefit from GIA’s new diamond cut grading system. By using the wider ranges for well-cut diamonds identified by GIA’s research, manufacturers potentially will be able to achieve more yield from rough. ---GIA Software and Grading Reports To aid all levels of the diamond trade, including manufacturers, retailers and appraisers, GIA is developing reference system software that will soon be available to provide predicted overall cut grades based on proportion information (such as crown angle or table size) and other quality factors (such as finish) input by the user. GIA intends to provide simplified versions of this software (which will be available on the GIA website) free to consumers and members of the diamond trade. More detailed versions will also be available for those involved in diamond manufacturing. In addition, GIA plans to offer the software as an embedded function in optical measuring devices (such as those offered by Sarin and OGI). Versions of the software will also provide the ability to compare the results from two different proposed diamonds, view “wire frame” diamond profiles for proposed diamonds, and print the calculated results. In the near future, GIA will incorporate the findings from its research into its Education courses, various presentations, and informational brochures for the consumer and trade. The institute also plans to incorporate the results of their diamond cut research into the GIA Diamond Grading Report and GIA Diamond Dossier® for all standard round brilliant diamonds in the D–Z color range for Flawless to I3 clarities. Each new GIA Report and Dossier® will include an overall cut grade, expanded proportion information in the form of a new diamond profile graphic, and a brief explanation of the Four Cs. GIA plans to announce their new reports in mid 2005. Articles cited above are available at http://www.gia.edu/gemsandgemology/27540/free_article_downloads.cfm.