How Diamonds Are Graded? Going Beyond the 4Cs

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The four Cs of the diamond world are quite famous even to those outside of the industry. Carat, color, cut and clarity are known as the four main criteria to grade a diamond and that dictate its overall quality and price.

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If you take the time to delve deeper into the subject matter, however, you’ll start noticing that there is quite a lot more that goes into grading diamonds. There are many sub-factors that contribute to each of the four Cs and there are many side factors that affect the quality of the diamond without technically being a part of the four Cs.

Let’s take a look at some of the main factors that go into grading a diamond.

The 4Cs – How They Came About?

The reason the 4Cs exist as an international unifying grading system is to allow gemological institutes to grade diamonds independently from the jewelry vendors.

This was necessitated from the fact that customers needed to trust the grading reports of the diamonds they were buying. By taking control of the grading away from the vendors and placing it into the hands of objective (and often even non-profit) gemological institutes, the industry guaranteed the quality of all diamonds sold.

Nowadays, there are quite a lot of gemological institutes across the world. You may have heard some of the more famous ones such as the GIA (Gemological Institute of America), the IGI (International Gemological Institute), the AGS (American Gem Society), the HRD (Hoge Raad voor Diamant), the EGL (European Gemological Laboratory) and others. They can sometimes use some slightly differentiating grades and sub-grades, but the major grading methods of the 4Cs are kept nearly identical.

The lab that started the Standardized Diamond Grading method, however, was the GIA.

Back in 1953, they realized the need for a unified grading system and established the four Cs of diamond grading. Their goal was to create one diamond “language” that everyone across the globe understood and used, to ease every step of the manufacturing and retail process. And they succeeded – in just a couple of years the GIA had created and presented the diamond certificates that would document the 4Cs of every stone and other institutes had followed suit.

What The 4Cs Are and Which Is Most Important?

Carat, cut, color and clarity are the 4Cs of the diamond industry, but what do they mean exactly?

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Carat is probably the most misunderstood metric outside of the industry. A lot of people think of carat as a synonym of purity (as in gold karats) but it actually refers to the weight of the stone. This, of course, is directly related to the price of the diamonds as the bigger the stone is, the more expensive it’s going to be.

Keep in mind, however, that size and weight are still different – depending on the way the stone is cut it can be visually large but still be relatively light in weight.

Cut is always vital for a diamond’s quality and outlook. The cut of a stone literally governs how it looks. Cut doesn’t refer to the stone’s shape, however – that is entirely separate from it.

Instead, “cut” refers to the faceting structure, how well the stone is cut, if it has the correct number and quality of facets, their symmetry and proportion, and so on. With that in mind, it’s easy to view a diamond’s cut as its most important metric as the cut directly displays the diamond cutter’s skills and it dictates how well the stone is going to reflect light and how much it will sparkle.

Diamond shapes
A list of diamond cuts

Color is the next of the four Cs. As much as the cut depends on the skills of the cutter, the color is independent of them.

The color of a diamond comes from the various minerals and other microscopic materials that might be mixed within the stone. Diamond color is graded on an alphabetical scale from D to Z, with D being completely colorless, and anything from K to Z displaying noticeable color tinges.

Each subsequent color grade up increases in price, all else being equal. Understanding diamond color allows you to drop as far down on the scale as possible while still having a beautiful-looking stone.

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Finally, clarity is the fourth of the 4Cs. It refers to how clear the stone is from any internal inclusions and blemishes.

The fewer inclusions a diamond has, the clearer it is, and the higher it’s graded. The diamond clarity grade goes from IF (Internally Flawless) and FL (flawless), through VVS (Very Very Slightly Included) and VS (Very Slightly Included), to SI (Slightly Included) and S1 (Slightly Included).

All these grades usually have sub-grades such as VVS1 & VVS2, VS1 & VS2, and SI1 & SI2, with the second grades being lower in quality than the first ones.

Included diamonds can be much cheaper than flawless or Very Slightly Included diamonds and would typically be full of inclusions, but that doesn’t always mean that you shouldn’t buy them.

The fact of the matter is that the diamond clarity grades only take into account the size and the number of the inclusions but typically ignore the position of the inclusion inside the stone as well as its color.

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This means that a VVS2 diamond could have just one minor inclusion, but if it were dark and positioned in a very visible place within the stone, it would bring the beauty of the stone down. Alternatively, some I2 clarity diamonds can have multiple internal inclusions but if they are colorless and placed near the pavilion of the stones, they can be very hard to see.

This is important as diamond clarity dictates a significant portion of a diamond’s price. Even just the difference between I1 vs I2 diamonds can make for a price increase of several hundred dollars or even more. Therefore, finding with a lower diamond clarity grade but visually unnoticeable inclusions is a great way to save some money.

Of the 4Cs, when it comes to colorless diamonds, we would argue that the order of importance is cut, clarity, color and carat.

What Is The 5th C in The Diamond Industry?

You might have heard of a 5th C as well – Certification. This isn’t always mentioned as it isn’t something that describes the stones themselves, but it is vital for a good purchase.

Buying a diamond that’s certified by a reputable and trustworthy gemological institute simply guarantees that you won’t be cheated with a lower-quality stone. After all, we can’t all be specialists and perfectly judge the diamond jewelry we’re purchasing.

Of all the grading labs, the Gemological Institute of America (GIA) is considered the best. It focuses on educating the consumer with detailed and comprehensive diamond guides and its criteria is stringent when it comes to grading diamonds. As an example, what might be considered a colorless diamond by another lab could be downgraded to near-colorless by the GIA. This is why when you purchase a GIA certified diamond, you know you’re getting your money’s worth.

The American Gemological Society (AGS) is also generally considered to be on par with the GIA. They provide quality certification and their criteria is also stringent. Both the GIA and the AGS follow a scientific process in evaluating diamonds.

Most other labs are not on par with these two grading labs and their criteria can be more relaxed, meaning that a sub-par diamond could be given a higher grade than it deserves.

Is A Grading Report Everything?

Diamond grading

Getting a trustworthy grading report for your stone is a great boon as it guarantees the stone’s quality and it tells you quite a lot about it.

At the end of the day, however, it still isn’t going to tell the full story of a diamond stone. There are just too many outside factors that can contribute to a stone’s appearance, so every stone should be judged by its own look and not just by the piece of paper it comes with.

A diamond can have a lower diamond clarity grade, but its inclusions can be unnoticeable and therefore irrelevant. A stone can have a slight color tinge giving it a mediocre color grade, but the right setting, side stones, and metal can make it work advantageously.

A diamond can also be of a relatively low carat weight but its shape, design, and setting can make up for that and make it look larger than it is. Even the cut of a diamond can be imperfect and have a couple of flaws, but a good jeweler can work around that and place it on your jewelry in such a way that hides these imperfections entirely.

The best way to judge your diamond is to closely examine it to ensure that it looks good and has excellent light performance. Don’t go on the report alone.

What’s the So-Called 6th C?

Conflict free diamonds

It seems the industry keeps adding Cs to the list. You might have also heard of a 6th C – Conflict free. This term has grown in popularity in recent years as the industry is trying to put an end to conflict diamonds, also known as blood diamonds.

For a stone to be considered conflict-free it has to be mined and sourced from a conflict-free mine in a country that has subscribed to the Kimberley process.

These days, consumers also care about how ethical and sustainable the stone is, and want to know that the stone has been mined under ethical working conditions with minimal environmental impact.

The 4Cs of diamond grading revolutionized the diamond industry about 65 years ago and made it much easier for customers worldwide to choose the best diamonds for their needs.

Still, the 4Cs aren’t everything and every stone you buy should first and foremost have the visual qualities and appearance you want.

Dani Rhys

Dani Rhys has worked as a writer and editor for over 15 years in the jewelry niche. She holds a Masters degree in Linguistics and Education. She has always been interested in expression through fashion and accessories, and her extensive experience in the field has made her a respected voice in jewelry trends and education. As the chief editor of Jewelry Shopping Guide, she not only leads the content strategy but also shares her insights through engaging articles. Her passion for storytelling is reflected in every piece she curates, exploring the intricate relationship between jewelry and personal identity.

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