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Round Brilliant Diamond Shape: Some Notes.
GIA updated the wording and the placement of “brillianteering” comments on its Diamond Grading Report and Diamond Dossier® for standard round brilliant diamonds as of July 1, 2006.
GIA’s new Diamond Grading Report and Diamond Dossier®, in January 2006, indicated when a diamond’s cut grade was affected by painting or digging out by putting a notation within the report’s comments section that read: Cut grade is based on brillianteering of the half-facets.
As of July 1, this statement will be located under the proportion diagram –-not in the comments section-– that reads: Cut grade affected by brillianteering.
Brillianteering refers to the last steps of the polishing process when the star facets along with the upper and lower half facets (also known as upper and lower girdle facets) are polished on the diamond. When a diamond is painted or dug out, these facets are polished in a manner that can affect the face-up appearance of the diamond and therefore may affect the final cut grade.
New location for comments on Girdle thickness.
Here is an illustration of an even and correctly proportioned girdle.
Here is an illustration of a "dug out" girdle. Note the uneven and very thin areas. This is usually done in situations where there may be large naturals, indented naturals, large imperfections,or other problems such as difficult cutting grains that the manufacturer needs to better control in order to save weight and/or make the diamond more saleable This may at times come at the expense of Symmetry in that facets are mis-aligned. This can also have a significant negative effect on light performance.
Here is an illustration of a "painted girdle". Note the extra thickness at the meet points of the upper to lower half facets These facets are cut shallow with a minimum of definition and resolution, hence "painted" onto the diamond so that the cutter can retain maximum carat weight.
May or may not have a negative impact on light performance and physical evaluation or additional information such as a Gemex Brilliancescope Light Analysis Report and Imagescope can be very helpful.
And just to review for newcomers to our DiamondVues Blog, the illustration below shows the various facets that comprise the round brilliant diamond shape. In all, there are 58 facets for the round diamond.
