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A diamond’s value is measured by all it’s different characteristics like shape, color, size, carat weight, clarity and cut, according to their respective importance. Know how to check the quality of diamond.
For instance the cut quality is more important than the color. The 4Cs are the best way to start understanding how to value your diamonds. They determine the diamond’s quality.

Diamond Quality – The 4Cs

In order to assess the quality of diamonds, experts gain knowledge and experience over a long period of time, to make sure you get the best quality for your money. The American Gem Society (AGS) has noted on the subject at length, and there’s a systematic rating system that the experts use to appraise your diamonds and find the exact quality grade according to your diamond’s characteristics. If you understand and use the same appraising techniques as the experts before you buy a diamond, it will greatly increase the chances of your purchase being a great one.


To get the full picture of a diamond’s quality, 4 different aspects are taken into account – these are the 4Cs of a diamond:

  • Cut – the shape and proportions of the diamond.
  • Clarity – the amount of inclusions or blemishes on the surface or inside the diamond.
  • Color – the amount of color or the lack thereof in a diamond.
  • Carat Weight – the weight of the diamond in carats.

Along with the certificate from a professional entity like the AGS or GIA, the quality is measured by the 4Cs.
All parts are important, but the Cut has the highest priority. We can now dive deeper into the 4Cs and understand the technique that experts use to appraise diamonds. Since all diamonds are made of the same chemical composites, their size determines the carat weight.


1. A Diamond’s Carat Weight


This is the only characteristic of a diamond that is 100% technical. A diamond can only have one size and weight, and there’s no debate about it, i.e. its either a 1 carat or a 2 carat diamond. Since larger diamonds are rarer, they are valued exponentially higher than smaller ones. The best way to calculate carat is with decimals rather than fractional weight. But you should know full well that at stores the jewelers tend to round up the numbers, so at times a 1 carat diamond may be in actuality only 0.89 carat weight.This of course is done to upscale diamonds for better sales. Keep in mind that a 0.89 carat diamond is less valuable and thus should be less expensive than a 1 carat diamond that has the same other Cs.

We must always keep in mind the other parameters that affect the diamond’s worth, as two diamonds with identical carat weight may have a different cut, color or clarity. For instance two diamonds with similar carat weight; the one with the lesser color, cut or clarity qualities will be far less expensive. In other words don’t be fooled by a bigger carat number when comparing two diamonds as the AGS explains so eloquently. Another thing to keep in mind is the optics of diamonds; some cuts, shapes and clarities may refract and disperse light better than others and thus these diamonds may seem larger when looking at them.

For instance a one carat cushion cut diamond may seem smaller than a round or emerald cut diamond with the same weight. It’s not an illusion of some kind, only the shape of the diamond from certain angles. The thing to remember here is to take into account all the 4Cs and their quality, not only the weight of a diamond.

2. A Diamond’s Color Quality

Just as all the other Cs the Color also has a big sway over the diamond’s quality. An ideal diamond is completely colorless, and even the slightest hint of color may diminish the quality of the diamond drastically. As you descend on the color scale, some yellow or even brown tints may appear and reduce the quality exponentially. The Gemological Institute of America (GIA) explains that most colors are not visible with the naked eye, but they still make a huge difference in the quality of a diamond and its value. With this rule of thumb comes a special exception; some specific colors are considered “fancy colors” like the canary yellow or even more rare – the red diamond. In these specific, exceptional and very rare cases the diamond value may increase substantially.

There are a total of 23 color grades on the color scale ranging from D to Z and they are grouped together to mark the different qualities of the colors.

The GIA color scale:

  1. Colorless – grades D-F
  2. Near Colorless – grades G-J
  3. Faint – grades K-M
  4. Very Light – grades N-R
  5. Light – grades S-Z

Remember that the closer the diamond to a colorless grade the higher the quality, but this is a very subjective feature in the 4Cs. There are several factors that may impact the color test, from the surrounding materials like the type of metal setting, to even the gender of the tester; It’s statistically known that women are more sensitive to color variants than men. For instance a one carat colorless diamond may be of higher value than a 4 carat diamond with an S color grade. Here is an expert technique you can try to test the color quality of your diamond. Make sure to place your diamond on a white sheet of paper in a well-lit room. Place the diamond on the paper with its table (top flat part) down. This will make any tint of the diamond’s color much more visible. Then get closer and closer to the diamond, and decide what is the distance you can notice the color compared to the price you’re willing to compromise on. In the end it’s important to remember that color grading is determined by the bottom part of the diamond, while usually we look at diamonds from the top, so it’s a good idea to test the diamonds from all directions before a purchase.

3. A Diamond’s Clarity Rating

Clarity is another important aspect of your diamond.

This is the measure of the amount of inclusions or surface roughness or imperfections a diamond has. A low clarity rate means that a diamond’s inclusions will be visible with the naked eye of an untrained viewer, while a top quality diamond will be flawless even when testing with the best equipment. Since lower clarity rating is much more common in nature, and thus the higher the clarity the more valuable the diamond is, according to the AGS notes. The clarity also affects the amount of light a diamond can refract and disperse, so a higher clarity diamond is much more brilliant than a lower quality one.
Moreover, higher quality clarity diamonds are much less prone to chipping, cracking or shattering especially if there are no inclusions on the edges of the diamond.

It’s important to remember that there are a total of 11 clarity grades, and that they are all tested under a 10x magnifier.
Diamond clarity grades are:

  1. Flawless (FL) – no inclusions or blemishes.
  2. Internally Flawless (IF) – no internal inclusions; might have slight surface blemishes visible under magnification.
  3. Very, Very Slightly Included (VVS1) and (VVS2) – minute inclusions that are difficult to see under magnification.
  4. Very Slightly Included (VS1) and (VS2) – minor inclusions that are very easy to see under magnification.
  5. Slightly Included (SI1) and (SI2) – noticeable inclusions under magnification that are also visible to the naked eye.
  6. Included (I1), (I2), and (I3) – obvious inclusions that are easily visible by the naked eye.

Keep in mind that clarity levels that are slightly flawed, but the inclusions or blemishes are not visible by the naked eye are common and therefore significantly less expensive than the most rare flawless diamonds. These diamonds look pretty much the same to most, and are known in professional circles as “eye clean” diamonds. Most people are very happy with these diamonds as they are much less expensive than the flawless diamonds. A great option is to always ask your jeweler to use their loupe to test your diamond, but it does require some expertise to detect the clarity quality. When you do it move away from the powerful lights that most stores have, since they may give excessive brilliance to the diamonds and obscure the actual clarity.

4. A Diamond’s Cut Quality

The shape of a diamond is an important part of the overall look, but it also affects the diamond’s popularity. This is why the cut is very important and at times the first thing any buyer would take into account prior to any of the other Cs a diamond has. Evaluating the shape of a rounded cut diamond like round cut and emerald cut is very objective, but the beauty of any other cut shape is a matter of personal taste and thus very subjective. The AGS says that a good cut diamond will have a much more brilliant sparkle even when it’s dirty, while a poorly shaped one will lose its luster with a little dust. The cut of a diamond is not only the shape but also the quality of the cut itself.

There are three optical effects for a diamond:

  1. Reflection – or Brightness is how the diamond reflects light similar to a mirror.
  2. Refraction – or Fire is how the diamond refracts light with the prismatic effect, how it breaks white light into all its colors.
  3. Dispersion – or Scintillation is how the light plays between light and dark areas of the diamond, creating the diamond’s contrast.

The contrast of the diamond gives it a much sharper appearance. The 10 point scale used by industry professionals to grade the quality of the cut may be slightly different at different grading laboratories. But knowing the differences is essential to know the quality of your diamond’s cut.

The 10 grades of cut quality according to the AGS are:

  1. Ideal Cut (0)
  2. Excellent Cut (1)
  3. Very Good Cut (2)
  4. Good Cut (3 to 4)
  5. Fair Cut (5 to 7)
  6. Poor Cut (8 to 10)

At times the cut quality is confused with the cut shape, but it’s important to distinguish between them. Cut shape is the overall shape of the diamond, like the popular round shape or other fancy shapes like pear, princess, and cushion. The cut quality is the proportions and symmetry of the facets, which allows for a much brighter brilliance on a great cut, or turns the diamond into a dull mirror with a bad cut. Contrary to many experts, the best way to test a diamond’s cut quality is not with special tools like the Holloway Cut Advisor, that can be very inaccurate, but to look at the diamond in a natural-light setting or even a low-light setting. It’s even better to use the vaseline test where you smear a little vaseline on the tip of the diamond to see if it’s still shining brilliantly when it’s a little dirty, and doing this in poor lighting conditions.

When you test it, move it around and see how it sparkles when the low light hit it – you’ll immediately see if you’re happy with the cut quality or not.

A Diamond’s Certification

Now that you know how to test the 4Cs and understand the different grades and qualities, you’ll need an accurate report of the 4Cs for the diamond you’re about to purchase. Taking up the word of a seller at face value is not the best practice as most are eager to make a profitable sale. When purchasing a diamond it’s important to get a certified report from a reputable gemstone association that needs to uphold a certain standard in order to protect it’s good reputation. The certification is an appraisal by an unbiased 3rd party, not by the buyer or seller, and is very important as there have been many diamond scams in the industry, where diamonds of lesser quality were passed as higher quality and thus more expensive, to unsuspecting novices. The 4Cs’ specifications for Cut, Color, Clarity and Carat weight will be included in the diamond’s certifications. Most certifications will have a computer generated image of the diamond with indications of it’s inclusions. The certificate will indicate the carat weight along with the proportions of the diamond and will have details about the color, cut and clarity. The certificate will also detail the origin of the diamond and have security measures to show its originality. These certificates are issued by one or more reputable diamond grading labs in the US or Europe.

Some of the reputable diamond graders that you should look for are:

  1. Gemological Institute of America (GIA)
  2. American Gemological Society (AGS)
  3. European Gemological Laboratory (EGL)
  4. Diamond High Council (HRD)
  5. International Gemological Institute (IGI)
  6. International Confederation of Jewelry, Silverware, Diamonds, Pearls, and Stones (CIBJO)

It is vital that your diamond has a certificate by one of the reputable entities in the market in order to avoid the many diamond scams. GIA has an online  “Report Check” that you can use to check and verify your certificate at any time by entering the certification number. When getting a certificate you must make sure its been given by an unbiased 3rd party, so do some research to make sure the seller does not own the lab certifying the diamond you wish to purchase. But as stipulated in this article, to really understand the certificate you’ll need to know how the tests are being done and exactly what they are grading. Having a basic knowledge of the 4Cs is paramount to making a great purchase and having a certificate from a reputable lab is essential. When purchasing a diamond it’s important to understand all the features that are combined together to determine its value. As the saying goes: “Diamonds are Forever” and so you’ll want them to keep their brilliance for a lifetime

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