The Proportion-Based Cut Grade system is scientifically vetted. Learn more at
Proportion-Based Cut Grade
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Proportion-Based Cut GradeAGS Laboratories’ Proportion-Based Diamond Cut Grade system is based on the AGS ground-breaking Light Performance system and is the only scientifically vetted proportion diamond cut grade system.

The AGS Laboratories technology team adapted the Light Performance methodology to proportion-based grading in an effort to give our clients more choices for the Round Brilliant diamonds they need graded.

In technical terms, the proportion sets were graded using the patented AGS Performance Grading software. The AGS Laboratories examined proportions over a 35-degree range of tilts in one-degree increments. Other proportion systems only look at the face-up position. This means that other methods are not as accurate as they could be. The new AGS methodology eliminates from its top grade the "steep/deep" combinations of other systems that have been a source of serious criticism within the scientific and cutting communities.

The AGS Laboratories’ Gold Diamond Quality® Report (DQR) features the Proportion-Based Grading system and uses an important word descriptor: Ideal(often known as Triple Zero). Of course, there are other descriptors as well:Excellent, Very Good, Good, Fair and Poor. Competitively, however, the wordIdeal gives your best diamonds a real advantage in this challenging marketplace.

While the Gold DQR provides the proportion-based cut grade for the Round Brilliant diamond, this format report can be used for other shapes as well, where a Cut Grade is not available. The AGS Laboratories Proportion-Based Grading system and the Gold DQR, thereby.
 giving you more choices.


Mission Statement

The American Gem Society (AGS) is a nonprofit trade association of fine jewelry professionals dedicated to setting, maintaining and promoting the highest standards of ethical conduct and professional behavior through education, accreditation, recertification of its membership, gemological standards, and gemological research.

The Society is committed to providing educational products to inform and protect the consumer and to contributing to the betterment of the trade by creating industry standards to protect the jewelry-buying public and the fine jewelry industry as a whole.

AGS Laboratories, founded to support the AGS mission, is a nonprofit diamond grading laboratory with a mission of consumer protection. Adhering to the AGS Diamond Grading Standards, AGS Laboratories is dedicated to offering diamond grading reports that provide consistency and accuracy based on science.

American Gem Society