An In Depth Look at the Upcoming GIA Cut Grading System
By Jonathan Weingarten (aka Rhino)
In the Fall 2004 Issue of Gems and Gemology, the GIA has released the specs of various diamonds and the grading classifications they are going to receive in their new and upcoming cut grading system. The GIA has been working with ray trace software to help determine their metrics along with the observance of many layman and professionals within the diamond trade and have provided 3 sample diamonds within each of their 5 cut grades which will be released mid 2005.
Using a similar type of software (courtesy of MSU) we have re-created a sample database consisting of the same diamonds they discuss in this issue. In addition, we will be including graphics that demonstrate the characteristics they are describing for each diamond along with sample .gem files of each (for you to open and compare) as well as my own commentary and experience regarding the optical properties of the diamond in question.
What is nice about this is the GIA has included sufficient minor facet information on each diamond to not only give a basic exam but to provide a more thorough one as they have come to realize the importance of minor facet cutting to the appearance of diamonds. For a thorough discussion on the minor facets (consisting of 40 out of 57 facets total) please consult our tutorial on the subject here.
The metrics GIA will include for the overall Grade will be those of
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brightness
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fire
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scintillation
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weight ratio
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durability
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polish
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symmetry
The total grade of the diamond will be determined by the lowest scoring factor. With regards to the major labs ... the bar is being raised.
To be able to download and view the Gem Advisor files included in this tutorial you'll need to download the free Gem Advisor software via this link. After you install the software you'll also need to open it up and open the sample file included. When you do this Windows will associate all .gem files and automatically open the files with the correct program. After you've completed these steps, to open a Gem Advisor file in this tutorial simply click on the MSU graphic included in the tables below.
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