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The 4 C’s Of Diamond Grading

If you are buying or selling a diamond you may have done some research and become aware of the importance of diamond grading. With different diamond grading laboratories using different grading terms and standards, we take a look at the standards used by the leading authority in gemology: the GIA.

Diamond Grading

You have likely have heard the term “the 4 C’s of diamond grading”. But what exactly are the 4 C’s and why are they important? In this article, we will take a closer look at the 4 C’s and answer the following questions:

  1. What is diamond grading?
  2. What are the 4 C’s?
  3. How do the 4 C’s affect the price of a diamond?
  4. How do you find out the 4 C’s of a diamond?
  5. How can I find out how much my diamond is worth?


What Is Diamond Grading?

Diamond grading is the act of assessing a diamond and grading it according to industry set diamond standards. When grading a diamond, a gemologist will first establish the 4 C’s of the stone. While these are not the only factors that affect diamond price, they are arguably the most important. Diamond grading laboratories such as the Gemological Institute of America (GIA), will then issue a diamond certificate that detail the characteristics of the stone.

The GIA is the leading diamond grading laboratory in the diamond industry. Their grading standards are the most stringent and the most widely accepted.

grading a diamond

What Are The 4 C’s Of Diamond Grading?

  1. Carat Weight
  2. Color Grade
  3. Clarity Grade
  4. Cut Grade


Let’s begin by going through each C that affects a diamond’s value:

  • Carat Weight

Carat weight, also abbreviated to ct, is the standard unit of measurement for diamonds and gemstones. The term carat comes from carob seed, a seed so uniform in weight (approximately 0.2g) that it became a popular unit of measurement in ancient times.

A carat weight is measured to the thousandth of a carat and rounded to the nearest one hundredth. Our Diamond Weight Calculator allows you to determine the carat weight of your diamond.


  • Color Grade

White diamond color grades range from D (colorless) -Z (tinted yellow or brown) . The more colorless the diamond, the more valuable it is. D color diamonds fetch more than Z diamonds as a poor color grade is low in demand, which deflates its value in the market.

The color grading scale for diamonds starts with the letter D and not the letter A, as diamond color was previously graded using the letters A-C (sometimes using multiple letter A’s), Arabic numbers (0, 1, 2) and Roman numerals (I, II, III). In order to avoid confusion and create a brand new color grading scale, the GIA chose the D-Z scale.

Color GradeDescription
G-JNear Colorless
K-MFaint (Slight visible tint)
N-RVery light (More visible tint)
S-ZLight (Noticeable yellow or brown tint)
I1, I2, I3Included (Flaws that are visible to the naked eye)


  • Clarity Grade

Clarity grade refers to the presence, or lack of, external and internal flaws. Flawless diamonds are rare and more expensive than flawed stones. Clarity grade ranges from IF (internally Flawless) to I3. Many flaws are not visible to the naked eye but have to be examined under a loupe.

Clarity GradeDescription
FLFlawless (No flaws externally and internally)
IFInternally Flawless (No flaws internally but some flaws externally)
VVS1, VVS2Very, Very Slightly Included (Slight internal flaws)
VS1, VS2Very Slightly Included (Slightly internal flaws but cannot be seen by the naked eye)
SI1, SI2Slightly Included (Slight internal flaws that may be seen by the naked eye)
I1, I2, I3Included (Flaws that are visible to the naked eye)


  • Cut Grade

Cut grade is how well a diamond can transmit light. This depends on its proportions (table, width, depth), symmetrical facets (girdle, pavilion, table, culet), polish (final treatment), brilliance (strong brightness & contrast), fire (distribution of colored light), scintillation (sparkle). Besides affecting a diamond’s value, the cut grade is also essential in determining its sparkle. Cut grades range from Excellent to Poor.

Cut GradeDescription
ExcellentMaximum polish, symmetry, brilliance, fire, and scintillation
Very goodMuch of the light is appropriately reflected
GoodLight is properly reflected but the fire and brilliance are not intense
FairLight escapes, and the fire and brilliance are quite dull
PoorDiamond appears dull with the light escaping the stone
4 c's of diamond grading

How Do The 4C’s Of Diamond Grading Affect A Diamond’s Price?

  • Carat weight: the price-per-carat of a stone increases as the weight increases. The larger the carat weight of a diamond, the larger it appears in size. There are certain “magic numbers” when it comes to carat weight, for example a 1ct is worthy significantly more than a 0.99ct diamond of the same quality. The same is true of a 2 ct vs a 1.99ct and a 3ct vs a 2.99ct and so on.
  • Color grade: the closer the diamond to a D grade, the greater its value. As mentioned above, the grading system ranges from D-Z with D (colorless) being the best color grade and Z (yellow tint/brown) being the worst. While a diamond may appear to be completely colorless, most diamonds do have a hint of yellow upon closer inspection and close comparison to other diamonds.
  • Clarity grade: the more flawless the diamond, the more valuable it is. However, just because you cannot see any eye visible flaws, does not mean that the diamond is flawless. Many flaws are only visible under a loupe.
  • Cut grade: ranging from excellent to poor, a good cut grade will increase the value of a diamond . In some situations, a diamond may undergo a re-cut to earn a higher cut grade. However this will mean losing some carat weight.

How Do You Determine The 4C’s Of A Diamond?

Most diamonds come with a grading report coming from certified laboratories such as the Gemological Institute of America (GIA), American Gem Society (AGS), European Gemological Laboratory (EGL), and International Gemological Institute (IGI). Not all laboratories are the same however. The GIA is widely recognized as the most accurate and trustworthy of diamond grading entities. Some laboratories do have a history of inflating the grades and providing certificates of varying accuracy.


How Can I Find Out How Much My Diamond Is Worth?

Most jewelers offer an appraisal service for a fee. However this will simply detail the characteristics of your stone, it will not enable you to ascertain its resell value.

A few things to remember:

  1. Insurance or appraisal values are extremely inflated and not representative of a diamonds’ value on the secondhand market.
  2. The resell value of a diamond is typically 25%-45% of what was paid at retail.

If you are looking to sell your diamond for a competitive price with no fees involved, WP Diamonds is your solution. A leading online diamond buyer, we offer a fast and safe selling experience; with GIA trained gemologists on hand to examine your diamond and make you a cash offer. Simply fill out the online form to receive your price quote, the entire selling process can take as little as 24 hours.

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535 5th Avenue, 11th Floor,
New York, New York
10017, USA

Berkeley Square House
Berkeley Square, Mayfair
London, W1J 6BD, UK

212 JQ Modern
120 Vyse Street, Hockley
Birmingham, B18 6NF, UK