By now we all know that the cut of a Diamond Determines it’s SparkleSat, December 23, 2006 - 1:31 PM
The GIA (Gemological Institute of America) launched it’s long awaited and highly publicized Cut Grade analysis on it’s Diamond Quality Certificates this past January.
The AGS (American Gem Society) has been including their version of Cut Grades during the past year (2005).
Mr. Cohn has found, after careful and detailed analysis that his program produces a simplified result comparable to either of the two aforementioned.
Mr. Cohn and his partner Peter Pedrotti have installed a Free of any charge Calculator that determines the eCS of any shape Diamond on their website at www.e-praise.com.
USE OUR FREE CALCULATOR TO DETERMINE
OF ANY SHAPE DIAMOND++++++GO TO www.e-praise.com and click on the eCS in the bottom paragraph
of our front page
This EGL Certificate was lifted from the Diamond Talk Site along with data seen in the comparison chart below.
The New e-Praise Cut Score (eCS) and the Importance of Cut Proportions
Too Shallow(eCS < 1.000) Ideal RangeeCS = 1.000 Too Deep(eCS < 1.000) "Fisheye" Brilliant "Nailhead"
THIS IS FULLY ILLUSTRATED ON OUR WEBSITE
well-accepted conceptual frameworks for professional diamond dealers and appraisers, but may not be directly helpful to the retail customer in selecting the best diamond for the price. The images above illustrate the simplest example of how the path of a single light ray entering the top table facet is redirected by internal reflections in differently crafted diamonds. If the cut proportions are either too shallow or too deep, a large portion of incoming light "leaks" from the bottom pavilion facets, reducing the amount returned to the viewer. Exactly which combination of cutting angles should be deemed to be in the "ideal range" has been debated since Marcel Tolkowsky's landmark analysis published in 1919. At e-Praise, we have developed a much simplified approach that uses the diamond's reported scalar measurements to compute an e-Praise Cut Score (eCS). The eCS places a diamond's geometric proportions on a fractional scale. If the diamond's most important proportions are within the ranges widely accepted as providing the most brilliance in each of the popular diamond shapes, its eCS is equal to 1.000. A lesser score, such as 0.992, indicates that the diamond's proportions are less "ideal", and the gem is expected to have less sparkle because it was cut too shallow or too deep.
Our appraisal formula applies value adjustments for each of the features of shape, finish, polish, culet size, girdle thickness and so forth that are recorded in the laboratory quality report. These relative value corrections are well established in professional appraisal practice. We treat the geometric proportions separately. The diamond is analyzed to determine if further changing one of its more important dimensions could have improved its "brilliance". If so, its value is recalculated based on this theoretical adjustment and only then is evaluated for its other features. The amount of any necessary modification is reflected as an eCS less than 1.000. The meaning of a diamond's eCS is simple to interpret. For example, a score of 0.990 indicates that as little as a 1.0% alteration of a diamond's proportions could have brought out its very best brilliance and fire. A small improvement in proportions potentially adds dramatically more beauty and value than is lost by a small reduction in carat weight. Using our "expert system", our monetary value results closely parallel the seemingly "subjective" opinion of expert appraisers with many years of experience comparing diamonds.
This is not to mean that we recommend the actual re-cutting of a low-scoring diamond, but that we encourage buyers to choose gems as close to eCS=1.000 as will fit in their budgets. This makes selecting the "most for your money" a simple task. A diamond's eCS should be known to any prospective buyer. We recommend that every high-quality diamond include a certificate as independent scientific evidence of its craftsmanship. If you are interested only finding in your diamond's eCS value, we now offer this important calculation as a free service.
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