What is AGS Certification?

by Willyou.net * Jun 2, 2021
What is AGS Certification

AGS (American Gem Society) is one of the pioneers in the diamond industry and known for creating the gemstone grading system, using a scale of 0-10, for the classification of diamond characteristics. It is one of the world’s most respected gemstone laboratories, and gems with an AGS certification ensures the quality of the diamond.

The History of AGS Certification

The American Gem Society, AGS, was founded in 1943 by a small group of retail jewelers who had the interest of buyers in mind, aiming to protect them against fraud in the diamond industry. They are bound to uphold the highest standard of ethics and integrity to the diamond industry. 

In 1996, AGS was the first organization to establish its own gemological laboratory to create a diamond cut grading system that consumers could read and understand. They accurately and consistently graded diamonds using their 4C’s grading system, providing consumers with a greater amount of education and clarity in choosing a diamond.

AGS Diamond Grading

AGS’s diamond grading is categorized by 4 C’s: carat, color, clarity, and cut on the 0-10 scale. Each diamond is analyzed and graded by at least two gemologists, based on these four qualities.


Grading a diamond’s carat is based on its weight, not it’s size. AGS measures the carat weight to the third decimal place using a digital carat scale, with the actual size of the diamond in millimeters (mm).  

For example, a one-carat diamond is equal to 200 milligrams (0.2 grams). Two, 1-carat diamonds can be completely different sizes, since they are measured in weight, not in size. 


Color grade is determined by how white or colorless a diamond is. AGS grades diamonds on a color scale from 0-10, with 0 being the most colorless and 10 containing a yellow or brown color tint. 

You can see from the scale below how AGS grades the color of diamonds on the 0-10 scale, compared to the GIA letter scale. The color grade given by AGS helps identify the quality of the diamond’s color. 

(image of AGS/GIA color grading letter scale)


AGS grades clarity on how clean a diamond is from inclusions and blemishes and is determined by examining the diamond with a binocular microscope under specialized lighting. 

The diamond’s clarity is based on the 0-10 scale, with a score of 0 being completely flawless up to a score of 10 which includes flaws.

(image of AGS/GIA 0-10 scale)


A diamond’s cut grade given by AGS is a bit different than other grades, as it’s given both a number and a word grading. Using a computerized device with revolutionary hardware and software to create a three-dimensional model of the diamond, AGS rates values for light performance including brightness, dispersion (fire), leakage, and contrast. 

The diamond is then analyzed for its proportions, such as girdle, culet, weight ratio, durability, and tilt. A diamond’s finish is determined based on polish and symmetry. 

As you can see from the AGS grading scale below, a score of 0 is an Ideal score with a score of 10 is a Poor score. A diamond can attain the coveted, “000’ score, if it reveals an optimum light performance, proportions and finish. 

(image of AGS 1-10 scale)

A grade of Ideal and Excellent grades, depending on Shape, demonstrates proportions and angles cut for maximum fire and brilliance.

(image of shallow, ideal, and deep diamonds)

AGS Quality Report 

(image of report)

Benefits of an AGS Certification

The AGS is a highly respected certification and having a diamond certified through AGS has many benefits. First, the certification offers a reliable grading for the diamond. It also ensures that your diamond has been analyzed by the best in the diamond business, and that you’re receiving the diamond quality that is stated on the certificate. It provides a peace-of-mind about the authenticity of your diamond as well as the high security measures taken to grade the diamond.