August 8, 2005
GIA Finalizes Cut Grade System
The Gemological Institute of America will include a cut grade for round brilliant diamonds on every GIA Diamond Grading Report and GIA Diamond Dossier®, starting Jan. 1, 2006. GIA President William E. Boyajian said the diamond cut grade is intended to be easily understood and implemented by all professionals in the trade. It was designed with a clear goal of instilling consumer confidence in the purchase of a diamond, he said. There's five-month's lead-time to allow the industry to study the new system.
The technology GIA employs to achieve a diamond's cut grade is open and available for use immediately, in the same spirit GIA's International Diamond Grading System is used around the world, said GIA. That system was developed over half a century ago and grades a diamond's carat weight, color, and clarity. Gemologists and labs soon adopted it as a global standard for communicating a diamond's attributes, known as the 4Cs.
Until now, GIA's reports did not include the rather slippery and subjective topic of cut grade. Much as GIA established a language to describe carat weight, color and clarity, GIA's new cut grade system boils down to single descriptive words anyone can understand: Excellent, Very Good, Good, Fair and Poor.
In determining grades, GIA will consider brightness, fire, scintillation, weight ratio, durability, polish and symmetry. Measured proportions will include total depth, table size, average crown angle, average pavilion angle, average star length and average lower-half girdle length. Visually assessed parameters will include girdle thickness, culet size, polish and symmetry.
The new cut grade will be used on diamonds D-Z in color, Flawless to I3 in clarity and in the same size ranges othat normally pass though its laboratory. Initially, the grading system will not apply to fancy-color or fancy-shape diamonds, or to round diamonds modified with different faceting arrangements.
For more information go to www.diamondcut.gia.edu.
by Robert Weldon, G.G.