Mastering Diamond Grading: From Novice to Expert

The Basics Of Diamond Grading

Diamond grading is the grouping or arrangement of diamond qualities in relation to the 4Cs’ of a diamond.

diamond grading

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One of the most sought-after stones in the world is the diamond. They are valued for their beauty, uniqueness, and toughness.

In this case, diamond grading is useful.

The fundamentals of diamond grading, including the 4 Cs, as well as other elements affecting a diamond’s quality and worth, will be covered in this article.

Overview of Diamond Grading

The technique of determining a diamond’s grade based on its features is known as diamond grading. The cut, color, clarity, and carat weight of a gemstone are together referred to as the “4 Cs.”

Each of these elements has an impact on the worth and beauty of a diamond.

Diamond Grading’s Four Cs


The shape and facets of a diamond are referred to as its cut. The diamond cut shows off a diamonds fire and brilliance.

Because the cut affects how effectively the diamond reflects light and seems to shine, it is essential. A diamond will seem more bright and flaming the better its cut.

A diamond’s cut primarily consists of three elements:

Dimensions: A diamond’s dimensions have an impact on how well it reflects light. The diamond won’t seem as bright if the proportions are off.

How closely the facets are aligned determines a diamond’s symmetry. The diamond will not reflect light equally if the symmetry is bad.

The smoothness of a diamond’s surface is referred to as its polish. The diamond won’t reflect light properly if the polish is poor.


Diamonds may be entirely colorless or they might be yellow or brown. On a scale from D (colorless) to Z (yellow or brown), a diamond’s color is rated. A diamond is more precious the less color it has.


The clarity of a diamond shows the presence or lack of inclusions…these are either carbon spots or small cracks.

These might be anything from big fissures to microscopic pinpoints.

On a scale from Flawless (no inclusions or blemishes visible under 10x magnification) to Included (inclusions and blemishes discernible to the unaided eye), a diamond’s clarity is rated.

Diamond Carat

A diamond’s weight is expressed in terms of carats. 0.2 grams are equivalent to one carat. The value of a diamond increases with its size.

This figure is correct on paper but doesn’t strictly apply in the industry.

This is especially so when converting rough diamond value to cut diamond value due to the 50% loss you experience during the cutting process.

The more a diamond qualifies to the left of one or all of the categories above, the rarer and the more costly it will be.

Meaning if a diamond has a D color, is internally flawless, is 2 carats in weight and has an ideal cut, and has a diamond certificate from the GIA or EGL it can fetch up to…wait for it $67,000 per carat.

The total cost for the stone being $134,000; that’s more than the annual salary of most senior engineers.

Additional Elements Affecting Diamond Value and Quality

There are more elements that might impact a diamond’s quality and worth in addition to the four Cs. These consist of:


Some diamonds display fluorescence when they are exposed to UV light. A diamond may seem milky or greasy as a result of this.


Obtaining certification is crucial when purchasing a diamond. It guarantees that the diamond has been examined by a reputable laboratory and complies with specified requirements. The American Gem Society (AGS), the International Gemological Institute (IGI), and the Gemological Institute of America (GIA) are the three most respected organizations for diamond certification.

Although the three organizations are all involved in the certification and grading of diamonds, there are notable variances between them.

  • GIA was founded as a nonprofit organization in 1931. It is one of the world’s most renowned and esteemed gemological laboratories. The Four Cs of diamond grading—carat weight, color, clarity, and cut—were developed by the GIA.

The Diamond Clarity Scale and the Diamond Color Scale, which are widely used in the industry, were both developed by the GIA. The GIA is renowned for its exacting grading criteria and is regarded as the industry’s gold standard.

Another nonprofit organization founded in 1934 is the AGS. The AGS is committed to promoting consumer education and safety.

It is renowned for its exacting standards and the fact that it imposes an ethical code on all of its members.

  • The AGS developed its own cut grading methodology, the AGS Ideal Cut, which is regarded as one of the most accurate in the sector.

ASET (Angular Spectrum Evaluation Technology), a special system used by AGS, is also used to evaluate the performance of diamond lights.

  • The IGI was founded in 1975 and is a for-profit company. It has sites all around the world and its headquarters are in Antwerp, Belgium.

Compared to GIA or AGS, IGI is renowned for its quick response times and is seen to be more approachable by the general population. Diamond grading, certification, and valuation services are provided by the IGI.

Along with grading and certification services for colored gemstones, IGI also grades pearls and jewelry.

The In-Depth Grading Process

The Eyes of a Gemologist

Grading a diamond is a meticulous process that demands the trained eyes of a gemologist and sophisticated instruments. Here’s a closer look at the process:

1. Diamond Inspection

A gemologist begins by inspecting the diamond under controlled lighting conditions. This helps in assessing the diamond’s color and the presence of any immediate blemishes or inclusions.

2. Magnification

Next, the diamond is examined under magnification, often at 10x, to identify the specific inclusions and assess their nature, location, and size. The clarity grade is determined based on these observations.

3. Angles and Proportions

For evaluating cut quality, the gemologist assesses the diamond’s angles and proportions. Tools like the Sarin machine or the Helium scanner are used to measure these parameters with precision.

4. Color Assessment

The diamond’s color is evaluated using master stones or precise colorimeters. Comparing the diamond’s color to a set of standardized stones helps in assigning the appropriate grade.

The Role of Accredited Laboratories

Reputable gemological laboratories play a pivotal role in diamond grading. They provide an unbiased assessment and certification of a diamond’s quality.

The most well-known and respected among these laboratories include the GIA, AGS (American Gem Society), EGL (European Gemological Laboratory), and IGI (International Gemological Institute).

When purchasing a diamond, a grading report from one of these labs provides transparency and assurance of quality.

Diamond Shapes

Round, princess, cushion, emerald, and other forms may all be found in diamonds. The value and look of a diamond may be impacted by its form.


The rarity of a diamond has a significant role in determining its value. Pink and blue diamonds, for example, are very uncommon and hence more expensive than other diamonds.

Certification has been recently added and a welcome addition it is!! So in effect, there are now 5Cs in total.

A diamond certificate is a document showing the above diamond qualities i.e. cut, clarity, color and carat for any diamond you buy.


Diamond grading is a complex procedure that involves evaluating its cut, color, clarity, and carat weight, in addition to other factors that influence its quality and value.

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