Beyond Carat, Clarity, Cut & Color:
The Details of Diamond Grading


A diamond grading report is an important tool in determining the value of a diamond.

A diamond grading report provides an impartial and professional assessment of a diamond’s characteristics. The measurements and gradings included in a grading report go beyond a diamond’s 4Cs (carat, clarity, cut, color) to provide diamond experts and gemologists a comprehensive view of a diamond’s quality.

Diamond grading reports are produced by professional grading labs, such as the Gemological Institute of America (GIA), American Gem Society (AGS), Gemological Science International (GSI), International Gemological Institute (IGI), and European Gemological Lab (EGL). A grading report produced by these and other labs provides an objective assessment of a diamond’s various attributes. The process of producing a GIA report number on a diamond, EGL diamond report, or other grading report involves evaluating a range of characteristics that only certified gemologists are qualified to assess.

A certified gemologist, also known as a graduate gemologist (G.G.), is a highly skilled professional that possesses the technical expertise and practical skills to evaluate gemstones. Gemologists must complete a certified gemological training program from an accredited school, such as the Gemological Institute of America, and pass rigorous course requirements to receive a diploma in gemology.

Diamond Grading

The importance of a diamond grading report

Unlike appraisals, the intent of a diamond grading report is not to assess a diamond’s value. Rather, a GIA grading report or AGS grading report provides information on a diamond’s characteristics, and in turn diamond buyers and sellers use the information as benchmarks to help price the diamond.

When producing a report (whether a GSI grading report or AGSL report), gemologists grade a number of intrinsic diamond characteristics. In addition to cut, clarity, color and cut, they look at attributes such as symmetry, polish and fluorescence to assess a diamond’s quality. It’s important that these attributes are accurately graded on a GCAL diamond report or other type of grading lab standard, for they help buyers and sellers determine a diamond’s value.

For example, symmetry and polish are key elements to understanding the quality of a diamond’s cut, and can significantly impact a diamond’s beauty and brilliance. The symmetry grade measures how symmetrical the diamond’s facets are, while the polish grade measures how smooth the diamond is after being cut and polished by a diamond cutter.

Fluorescence is another important attribute that is measured on an IGI grading report or other grading report. It refers to the strength of diamond’s reaction to long or short-wave ultraviolet light. A diamond grading report will note the degree of fluorescence within a diamond – gradually growing from None, Faint, Medium, Strong to Very Strong. Not all diamonds are fluorescent, and not all fluorescent diamonds are valuable. Generally, gemologists believe that fluorescence is neither good nor bad. However, fluorescence may cause some diamonds to appear milky, or cloudy, and this will negatively impact a diamond’s value.

GIA Report

While all labs are reputable, they sometimes use slightly different terminology to describe diamonds features. Where they can vary more significantly is in the scale they use to grade diamonds. As an example, a F color grade by one lab could be graded as G color by another lab.

Keeping a diamond grading report objective

To maintain a level of professionalism and credibility, grading labs strive to avoid any bias from influencing a diamond grading report. A GIA diamond grading report, EGL grading report, or other, should provide an impartial assessment of a diamond, and therefore anonymity of the client or diamond owner is crucial.

In fact, most grading labs have developed complex processes and inventory methods to ensure that a diamond is carefully handled and the diamond’s owner is kept anonymous throughout the entire grading process. While this may seem like an excessive precaution, it’s an important measure for labs to take because it helps maintain the integrity of an IGI, GSI, AGS grading report, or other diamond grading report.

Protecting a Diamond Throughout the Grading Process

Certified gemologists understand they are handling valuable items when they conduct an AGS diamond report, IGI grading report, or other. Each diamond, regardless of size, shape or quality, is handled with care and expertise to ensure its attributes are not compromised or altered during the grading process.

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It is clear that diamond grading is about more than simply evaluating the 4Cs. It’s a complex process designed to ensure complete accuracy and objectivity about a diamond’s quality, and can provide the benchmark information diamond buyers and sellers need to value a diamond.

When assessing diamonds, Mondiamo uses the GIA standard for diamond grading because GIA is considered the gold standard in the industry. It’s always important to remember, however, that to truly assess a diamond’s beauty, and therefore its value, it should be evaluated in person. Learn more about Mondiamo’s diamond evaluation process by visiting our Our Process page and watching the videos.