Diamond Grading 101: Decoding the Mystery Behind Each Stone

Wondering how diamond grading works? It’s a detailed yet essential process. Diamonds are among the world’s most precious commodities, coveted by many, regardless of size. So, how are diamonds valued, and what determines their price? This is where diamond grading comes in.

It’s the method used to evaluate and categorize diamonds, determining their true worth. Think of it as a way to assess the value of a diamond. In this article, we’ll provide you with all the essential details about diamond grading, breaking down its intricacies for you.

What is diamond grading?

Ancient cultures also valued and used diamonds, but they did not possess an evaluation system to offer a rating or grade. There were, in the early 1900s, investors, traders, and jewelers who ranked their diamonds as "perfect," "good," and "flawless," but these were relative and subjective terms.

The modern concept of diamond grading began in 1939, when the Gemological Institute of America introduced to the world the Four Cs, a standardized method for measuring the quality of a diamond.

The Four Cs—cut, color, clarity, and carat—are the standard parameters that set values on a diamond. Therefore, understanding the four parameters would essentially denote just how precious a diamond is.

Importance of Diamond Grading

Just like how a secondary school exam certificate is required to get into college, diamond grading serves as a standardized measure to evaluate a diamond's true value.

Without a clear grading system, it's impossible to know if you're getting what you’re paying for, much like how an uncertified exam score wouldn't be enough to secure your place in college. Grading ensures transparency, fairness, and that both buyers and sellers are on the same page when it comes to a diamond's worth.

The 4Cs of Diamond Grading

Just as an interviewer looks for specific qualities and traits in candidates before hiring them, a diamond grader evaluates a diamond using the Four Cs to determine whether it is real or fake.

If the diamond is authentic, the grader then assesses its quality. Let's explore each of the Four Cs in detail, one by one, in chronological order to understand how they contribute to determining a diamond's value.

First C of 4Cs: The Cut

 The cut of a diamond is the most important factor, as it determines the brilliance and sparkle of the stone, significantly affecting its overall appearance. According to the Gemological Institute of America (GIA), a diamond's cut is graded on a scale ranging from excellent to poor.

The higher the cut grade, the more valuable the diamond will be. The cut is a technical aspect that governs how light interacts within the diamond, creating its signature sparkle.

Second C of 4Cs: The Color

Color is the second most important factor in determining a diamond’s quality. While a diamond’s luster and sparkle are essential, color plays a crucial role as well. Diamonds come in a range of colors, from colorless to yellowish and brownish hues.

The purest and most valuable diamonds are completely colorless. As the color shifts from colorless to yellow and then to brown, the quality and price of the diamond decrease. To help categorise diamonds based on their color, the Gemological Institute of America (GIA) developed a color chart that assigns a specific grade to each hue.

Third C of 4Cs: The Clarity

Clarity is the factor used to determine how pure a diamond is. Believe it or not, clarity is one of the most challenging aspects of diamond grading. As diamonds form deep within the earth, they often contain impurities, known as inclusions, which can significantly impact their overall quality. The most valuable diamonds are those without any impurities, classified as "internally flawless." As the number and size of inclusions increase, the quality and value of the diamond decrease.

Fourth C of 4Cs: The Carat

Last but not least, the weight of a diamond is one of the most common factors used to determine its value. Just as human weight is measured in kilograms or pounds, the weight of a diamond is measured in carats. One carat is equal to 0.2 grams, so a diamond weighing 1 gram is equivalent to 5 carats.

How Diamonds are Graded

Diamonds are graded by professional graders who evaluate each of the Four Cs individually. Using specialised tools and grading charts developed by organisations like the GIA (Gemological Institute of America) and IGI (International Gemological Institute), graders determine which category a diamond falls into for each of the Four Cs.

By carefully assessing these factors, they can make a final determination about the diamond's overall quality. Let’s explore how each of the Four Cs is measured to categorise the diamond by quality.

Grading of Diamond Cut

It's important to know about the anatomy of diamond is made up of 57 to 58 facets in total, including the girdle, culet, top, and bottom. Together, these facets define the diamond’s cut. The role of the grader is to assess how well these facets are aligned and proportioned. To do this, the Gemological Institute has developed a standard set of aspect ratios. A diamond that meets these ratios perfectly is considered to have an "excellent" cut.

Tools for Diamond Cut Grading

• Loupe 10x and Other Scopes
• Microscope
• Grading Chart
• Sarine Systems
• Facetware Software
• Heathcoat’s optical bench
• Polish and Symmetry Evaluation Tools
• Crown and Pavilion Gauges

GIA Diamond Cut Grade Chart:

Grade	Description
Excellent	The diamond reflects nearly all the light that enters, creating maximum brilliance. The proportions and symmetry are near perfect.
Very Good	The diamond reflects most of the light that enters, producing high brilliance, but there may be slight imperfections in proportion or symmetry.
Good	The diamond reflects a fair amount of light, but some brilliance may be lost due to minor issues in proportion or symmetry.
Fair	The diamond has noticeable flaws in proportion or symmetry that reduce its brilliance. Light performance is significantly compromised.
Poor	The diamond has major proportion and symmetry issues, which cause it to lose most of its brilliance and sparkle.

Grading Of Diamond Color

Diamond color grading evaluates the presence of color in a diamond, with the most valuable diamonds being completely colorless. The Gemological Institute of America (GIA) developed a color grading scale to assess diamonds, ranging from D (colorless) to Z (light yellow or brown).

Tools for Diamond Color Grading

• Diamond Color Comparison Tray
• GIA Color Grading Chart
• LED Color Grading Light
• Color Grading Viewer
• Diamond Color Grading Master Set

Diamond Color Grading Chart

Grade	Description
D	Colorless – No color visible. The highest grade.
E	Colorless – Slight traces of color, only detectable by an expert.
F	Colorless – Minor traces of color, still considered excellent quality.
G	Near Colorless – A very faint trace of color, barely noticeable to the untrained eye.
H	Near Colorless – Slight color visible, but still a high-quality diamond.
I	Fair – Noticeable color, but still appealing.
J	Fair – Slightly more noticeable color, but still within acceptable standards for many buyers.
K	Light Yellow – Noticeable yellow or brown hue.
L	Light Yellow – More intense yellow or brown color.
M-Z	Faint to Light Yellow/Brown – Noticeably colored diamonds, less valuable.

Grading Of Diamond Clarity

Diamond clarity grading evaluates the presence, size, and visibility of inclusions (internal imperfections) and blemishes (external imperfections). The grading scale ranges from Flawless (FL), which has no visible imperfections under 10x magnification, to Included (I1, I2, I3), where inclusions are visible to the naked eye and affect the diamond’s transparency and brilliance.

The clarity grades include:

• Flawless (FL):  No visible imperfections.
• Internally Flawless (IF): No internal imperfections but may have minor surface blemishes.
• Very, Very Slightly Included (VVS1, VVS2): Inclusions are difficult to detect.
• Very Slightly Included (VS1, VS2): Inclusions visible under magnification but not the naked eye.
• Slightly Included (SI1, SI2): Inclusions visible under magnification and sometimes to the naked eye.
• Included (I1, I2, I3): Obvious inclusions visible to the naked eye.

Determinig a Diamond Carat

Carat is measured by weighing the diamond in metric carats. Each carat is exactly 200 milligrams or 0.2 grams. Now, the term for carat comes from the carob seed. Historically, it was used as a reference standard for weighing gemstones because of its uniform size. Today, modern digital scales weigh diamonds accurately to the hundredth - that is, to the 0.01 of a carat.

Differences Between Diamond Grading and Gemstone Grading

While both diamond grading and gemstone grading are evaluation processes of precious stones, each looks to focus on different issues due to the unique features of a diamond distinguishing it from other gemstones.

Grading Criteria:

Diamond Grading: 

Focuses on the 4Cs – Cut, Color, Clarity, and Carat Weight.

Gemstone Grading: 

Focuses on factors such as Color, Clarity, Size, Shape, Transparency, and sometimes Origin.

Focus:

• Diamond Grading: 

The Cut is the most critical factor, as it affects the diamond's brilliance and sparkle.

• Gemstone Grading: 

More emphasis on Color and Clarity, but each gemstone has unique grading considerations (e.g., Sapphire color richness, Emerald inclusions).

Grading Systems:

• Diamond Grading: 

Standardised grading scale (e.g., GIA scale: FL, IF, VVS, VS, SI, I).

• Gemstone Grading: 

Varies across different types of gemstones, with different scales and criteria (e.g., rubies, sapphires, emeralds have distinct grading systems).

Appearance Focus:

• Diamond Grading: 

Emphasizes the overall brilliance, fire, and sparkle based on the cut.

• Gemstone Grading: 

Focuses on color intensity, clarity, and the overall appearance of the gemstone.

Conclusion

Grading of diamonds is the most important process to ascertain the actual worth and quality of a diamond. Upon analysis of the Four Cs: cut, color, clarity, and carat weight, gemologists obtain a true, standardised assessment in a transparent manner, which both the buyer and the seller know what they are paying for.

This grading system not only helps individuals make wise purchasing decisions but also aids in keeping the diamond industry honest. Whether you are a user or a collector, knowing about diamond grading gives you the opportunity to appreciate the detailed differences that separate each stone. With this knowledge, you can make a better choice as you choose a diamond that fits your expectation, knowing that its beauty and value are certified and accurate.

FAQs: Diamond Grading

Difference Between Flawless and VS Diamonds

Those diamonds classified as Flawless (FL) possess no inclusions or blemishes at a 10x magnification. They are, therefore, very rare and expensive. In contrast, diamonds with Very Slightly Included (VS) characteristics possess minor inclusions hard to view even at 10x magnification and are usually not visible by the naked eye. 

What Are SI Clarity Diamonds?

SI clarity diamonds are those that contain inclusions visible under 10x magnification and sometimes to the bare eye, and more or less for SI2. SI diamonds tend to be quite popular since they will indeed give a high-quality appearance at an affordable price, thereby making diamonds very accessible to most customers.

How Does Diamond Color Influence Its Grade?

Color grading refers to the color of a diamond. A diamond is graded colorless, while from D to Z being light yellow or brown. Colorless diamonds are very valuable for the simple reason that without color, there is more room for the light to be reflected for brilliance. Even small color differences can be hugely important in terms of value; the most expensive ones tend to be the colorless diamonds.

What Does the Diamond Grading Report Include?

A diamond grading report, for instance, issued by the GIA or AGS, includes an assessment of a diamond's 4Cs: cut, color, clarity, and carat weight, plus many more details about proportions, polish, symmetry, and fluorescence. In fact, it is a quality and authenticity certificate.

GIA vs. AGS Grading-What's the Difference?

GIA uses an alphabetical scale (D-Z) for color and qualitative terms for clarity, whereas AGS uses a numerical system (0-10). AGS is particularly noted for having very detailed grading for cuts, which is why it is primarily in demand by the consumers, who are fussier about that cut. Both have very high credibility regarding grading diamonds.