American Gem Society Homepage  |  Contact Us  

AGS Laboratories FAQs

AGS Laboratories offers diamond-grading services to members of the jewelry industry. Our diamond grading reports benefit consumers by providing documentation of an expert opinion from an unbiased, independent third-party diamond laboratory. We grade loose diamonds. Our standard grading services include the 4Cs of diamond grading: carat weight, color, clarity and cut.

Any diamond shape can receive a diamond grading report, but we only assign an AGS Cut Grade for loose diamonds that are round brilliants, square princess cuts, emerald cuts, oval cuts and cushion cuts, as well as some proprietary shapes.

We also grade fancy brown diamonds with our own Chroma Signature system; learn more here.

To verify an AGS Laboratories diamond grading report, visit our AGS Laboratories Report Verification page. You can verify the information on your diamond grading report matches the information stored in the AGS Laboratories report database.

If you’re not in the jewelry trade, please visit a local American Gem Society retail jeweler. An AGS retail jeweler may be able to submit the diamond to the AGS Laboratories for you. If your business is in the jewelry trade, we’ll be happy to set up an account. Please see our information about how to Become a Client or call client service.

If you’re not in the jewelry trade, please visit a local American Gem Society retail jeweler. An AGS retail jeweler may be able to submit the diamond to the AGS Laboratories for you. If your business is in the jewelry trade, we’ll be happy to set up an account and inscribe your diamond. Please see Become a Client.

If you’re a consumer, you may request a replacement AGS Laboratories grading document directly from the Laboratory. If there are any issues ordering a replacement AGS grading report, please contact us. If your business is in the jewelry trade, we’ll be happy to set up an account and provide a replacement document.

You can Find a Jeweler through American Gem Society.

Find a Jeweler

For jewelry appraisal you can trust, find a certified appraiser through American Gem Society.

Find an Appraiser

We grade loose round brilliant or fancy-shaped natural diamonds, brown diamonds, and laboratory-grown diamonds. The AGS Laboratories is a trade-only diamond laboratory and only accepts diamonds from jewelers and manufacturers. If you are a consumer and would like to have your diamond receive an AGS Laboratories diamond grading report, we recommend finding an American Gem Society jeweler in your area.

Find a Jeweler

The AGS Laboratories screens every diamond for potential treatments like High Pressure High Temperature (HPHT) treatment, fracture filling and laser drilling. The AGS Laboratories will grade an HPHT-treated diamond if the fact of its treatment is disclosed.

The AGS Laboratories does not grade fracture-filled diamonds or diamonds with any other treatment that is not permanent. However, the AGS Laboratories does grade diamonds that have been laser drilled if they’re not set in jewelry.

All treatments are disclosed in the “Comments” section of an AGS Laboratories diamond grading report.

You should take your diamond to be cleaned and inspected by a professional jeweler at least once a year. If you are cleaning your diamond at home, you can purchase cleaning agents at your jeweler. You may also use a solution of warm water and a mild liquid soap. Apply the solution to the diamond gently, using a cotton swab or soft bristle toothbrush; rinse thoroughly and dry with a soft cloth.

No. The AGS Laboratories provides an unbiased, independent and expert third-party opinion on the 4Cs of a diamond. You should never see an appraisal amount on a diamond grading report. Price of the diamond should be determined by the jeweler, not the laboratory.

Diamond Cut Grade FAQs


The jewelry industry refers to Cut in two ways:

  • As a reference to the shape, style, and faceting of a diamond
  • How well a diamond is fashioned (e.g., brilliance, fire and scintillation)

An AGS Ideal Cut is a diamond where all the diamond’s Cut quality factors (light performance, proportions and polish and symmetry) exist at the highest possible levels, making the maximum contribution to the diamond’s beauty and value.

The AGS Laboratories uses the AGS Performance-Based Cut Grade system, which is based on the overall performance of a diamond, specifically in the area of Light Performance. When analyzing the overall performance of the diamond, we take the following into consideration: light performance (contrast, leakage, dispersion and brightness), proportion factors (girdle thickness, culet size, weight ratio, durability and tilt), and finish (polish and symmetry).

In 2006, the American Gem Society released its fancy shape Cut Grade research, which concluded five years of research by a team of diamond experts, optical physicists and mathematicians. Currently, the AGS Laboratories grades princess, emerald, oval, cushion shapes, as well as others. The cut grade system is flexible; it can support a plethora of patented and proprietary shapes never seen before in the industry.

To learn more about the definitions of common cut-related terms please visit the GLOSSARY.


Clarity is the degree to which a diamond is free from inclusions and blemishes. Inclusions are internal characteristics; blemishes are external characteristics. Many diamonds have Clarity characteristics that can be seen only with magnification. The Clarity grade is subjectively based on the nature, location, size, quantity and relief of the inclusions. At the AGS Laboratories, a minimum of two experienced diamond graders will grade each diamond for Clarity.

Color normally refers to where a diamond’s Color falls within the range from colorless to light yellow or light brown. At the AGS Laboratories, the Color of a diamond is determined by at least two experienced color diamond graders using a set of master diamonds.

Each diamond grader must pass the Gemological Institute of America (GIA) Diamond and Diamond Grading courses. In the AGS Laboratories, several Certified Gemologists oversee the work of each diamond grader.

A minimum of two (2) diamond graders must analyzes and agree on each diamond factor.

Yes! At this time the AGS Laboratories grades brown fancy colored diamonds only; learn more about our brown diamond grading system.


Have a question that’s not listed here? Contact us at AGS Laboratories.