How to Grade Diamonds

How to Grade Diamonds

How to Grade Diamonds

Posted by Sharif Khan on 24th Sep 2018

We have all heard the saying that diamonds are a girl’s best friend. The truth is that it is what the diamond represents that really matters. When a man takes the time and money needed to purchase diamond jewelry, especially a diamond ring, he is making a promise to love and cherish her forever. Diamonds are a fitting symbol of true love. They have been around for centuries, and will continue to last through many lifetimes.

James Allen

Many people are shocked to learn that not all diamonds are the same. To the untrained eye, they may all appear to be crystal clear and equally sparkly, but that could not be farther from the truth. Each diamond is as unique as a fingerprint. It thus goes without saying that some diamonds will emerge as being of finer quality than others, and you would want to get the one that provides the greatest value for money.

Why You Need to Know How to Grade Diamonds

Often times, it is up to you to figure out which diamond is better for the occasion. A sales representative in a jewelry store is there only to do one thing; get sales. They may even be willing to do this at their customer’s expense. These sales representatives are also going to try to get you to pay the highest price possible even if that piece of jewelry is of inferior quality.

That is why it is imperative that before you attempt to make a major purchase like diamond jewelry, you at least take the time to understand the basics of how diamonds are graded. You should be able to confidently walk into any jewelry store and make an excellent selection when you are armed with this kind of knowledge. Now, let’s get down to the meat of the matter.

Diamond Grading 101 and the GIA

When grading a diamond, there are a few things that you need to examine. These are often referred to as the four Cs. They are:

  • Cut
  • Color
  • Clarity
  • Carat or carat weight

The four Cs is a concept developed by the GIA, which is professionally known as the Gemological Institute of America. This not-for-profit organization was founded in the 1930s and has since developed a standardized method for grading diamonds. Their methods have been world renowned because their evaluation techniques are fair, accurate, and reliable regardless of the value of the diamond or its location. Let us take some time to examine what each of the four Cs represents.

The Cut

Many experts believe that the cut is one of the most important factors when grading a diamond, although it is the most difficult to quantify. That is because the cut has a direct effect on how shiny or brilliant the diamond appears to be. Think about it, who of us would want to buy a diamond that is not brilliant and spectacular in appearance?

When the term cut is used, this refers to more than the shape of the diamond itself. Popular shapes include round, square, heart, oval, and triangular. On the contrary, the  cut of the diamond is an indication of its proportions, how symmetrical it is, and how well the stone is polished.

When a diamond is cut well, it will be evident in three main ways:

  • 1.The Scintillation - The diamond will sparkle when a light is shined upon it
  • 2.The Brilliance – The diamond will shine brilliantly and reflect a bright, white light from within and on its surface
  • 3.The Fire – The diamond will also reflect a visible spectrum of colors at certain angles

Bear in mind that diamonds are from humble beginnings and are first just rough stone-like formations. The diamond cutter must carefully examine the stone to devise the best way to cut the stone so as to highlight its beauty and maintain its carat weight.

The GIA scale for evaluating the cut of a diamond consists of five tiers. This scale ranges from excellent to poor. It goes without saying that diamonds graded as excellent would be the most brilliant. The GIA uses a number of measurements such as the crown height and total depth to assess the cut of each diamond.


Color is the believed to be the second most important factor when grading a diamond. The ideal diamond should be luminescent and crystal clear. It goes without saying that icy-white, transparent diamonds will fetch a much higher price than those with an obvious tint of color.

The GIA has determined that the  color of a diamond can be graded on a scale from D to Z. Diamonds with the least amount of color will be graded as a D, and diamonds with obvious tints of brown or yellow will be graded as or near category Z. Diamonds which are labeled grades D to H should be colorless or near colorless to the naked eye.

If the diamond has already been attached to a ring or another type of jewelry, note that it may reflect some color from the ring. This is especially so in the case of gold jewelry, which often gives diamonds a slightly yellow appearance.

The diamonds are graded this way because the presence of a yellow or brown tint significantly reduces its ability to reflect the brilliance or the fire that we have come to expect from our diamonds. These diamonds thus fetch a lower price because while they are beautiful in their own unique way, they will appear relatively dull or cloudy in their appearance. 


The clarity of the diamond refers to whether there are any inclusions of flaws on the diamond. The GIA scale for the clarity of a diamond ranges from flawless to I3. There are 11 categories on this scale.

A flawless diamond has no inclusions or flaws even when it is examined up to 10 times the normal magnification or 10x loupe. Only an experienced  gemologist would be able to detect these minute flaws.

When the inclusion or flaw is not visible to the naked eye, the diamond is referred to as an ‘eye clean’ diamond. These are among the rarest of all diamonds. In fact, less than 1% of the diamonds on earth fall into this category.

A diamond with a grade of I3 has very obvious flaws, which can even be seen with the naked eye. These flaws can include shards of other stones or scratches that might have occurred when the diamond was being cut or polished.

Stones at the lower end of the scale are much easier to find. You, however, need to examine your diamonds carefully before making your purchase. These flaws or inclusions may detract from the beauty of the ring. Also, two stones with the same rating may have flaws which appear completely different.

Just as no two diamonds are the same, no two inclusions are the same. You need to examine the diamonds carefully to determine which flaw is more obvious to you.

Carat Weight

The carat weight is by far the most popular method used to grade a diamond. When someone brags about their diamond jewelry, the first thing they will quote is the carat. It is highly unlikely that they will readily state anything about its cut or lack of flaws. That is why this is such an integral aspect of determining the grade of a diamond.

Firstly, it should be noted that this refers to the actual weight of the diamond and not its size. However, the size of the diamond does have incredible influence on the carat weight. Long ago, jewelers relied on the relatively uniformed sized of the beans of a locust tree, known as carobs, to determine the weight of a diamond. Many believe that this was how the weight of the diamond came to be measured in carats.

Regardless of how accurate that measure was, the name carat became synonymous with diamonds and precious metals like gold. However, when the term carat is used in reference to gold, it is describing the purity of the gold.

Today, we have developed much more reliable means to standardize the weight for diamonds. Sadly though, many do not believe that the carat weight should have much bearing on the value of a diamond. This could not be farther from the truth.

While diamonds are valued more for their brilliance than their weight, the carat weight of the diamond can be used to differentiate two diamonds of similar cut, clarity, and color. The diamond with more carat weight will fetch a higher price.

Also, as mentioned earlier, the carat weight is often determined by the size of the diamond. Larger diamonds provide a greater surface area for white and colored light to be reflected. Larger diamonds may thus appear more brilliant than smaller diamonds of a similar grade.

Larger diamonds often tend to be much more expensive than smaller diamonds, even when of inferior quality. That is because larger diamonds are cut from larger rough stones. These are rare and very hard to find when searching for natural diamonds, instead of  lab grown diamonds. The rarity of these diamonds thus allows jewelers to demand a higher price.

Many people are tempted to compromise on the cut of the diamond simply to get a higher carat weight. They would prefer the prestige of saying they have a 1 or 2 carat ring. Please do not make this mistake. Your friends and relatives will be far more impressed by a smaller diamond that is cut in a way to show off the best of its brilliance than a larger diamond that simply does not shine.

Now that all this has been said, you may still be wondering how you can choose the best diamond. Please allow me to provide a few simple suggestions.

How to Choose the Best Diamond

Jewelers have been in the industry for years, so it will be hard to challenge them if you are not an expert yourself. All you need to do is focus on the four Cs. Speak with confidence about what you do know, and they will be less likely to try and deceive you with an inferior quality diamond.

Be on the lookout for poorly cut diamonds that are dull in appearance. These do not reflect the kind of brilliance and fire that is associated with  well cut diamonds. Beware of crafty sales representatives that use specially lighted displays to trick you into believing their diamonds are of good quality. When in doubt, ask to see the stones in natural light.

Also, don’t be afraid to ask to see the diamond certification. You work very hard for your money and you deserve to get the best value for your money. If no diamond certification is available, compare the diamond being presented with one that has already been certified.

If your aim is to find the best quality diamond at the lowest price, try to compromise on the shape of the diamond than the quality. Avoid round shaped diamonds. Round shaped diamonds require that the cutter remove and even waste a lot of the stone in order to get a distinctly round shape.

It would also be wise to shop around. Do not feel compelled to take the first option presented to you. Jewelry stores in some locations tend to have higher prices than others. Compare the prices from a variety of stores and choose wisely. Why would anyone want to waste their hard earned money?

As you can see, there is a lot to consider when grading a diamond. This is especially so since each diamond is a unique blend of the four Cs. Whatever you decide, be sure to do a bit more research on the characteristics of the type of diamond you intend to buy. It would also be wise to only make your purchase from reputable jewelry stores or online dealers. Last, but certainly not least, take a long hard look at their return policy before handing over a few months worth of your savings.