A diamond’s 4 C’s represent the four main components of its beauty and structure: Cut, Color, Clarity and Carat.

When looking at a diamond, the eye perceives a balance of its characteristics and components, including, but not limited to, the 4 C’s.Each of the C’s are graded on a scale, and can be evaluated for quality. Gradings of the 4 C’s help determine the value of a diamond and indicate its quality. Diamond sellers often set their prices based on grading reports. Knowing the basics of these gradings is helpful when comparing two similar diamonds, but what remains most important is how the diamond appears to the naked eye—and how attractive the diamond is overall. In this sense, having a foundational understanding of the 4 C’s is imperative as a buyer, so that you can avoid spending your budget on a component that will go unnoticed.


Of all the 4Cs, Cut has the greatest effect on a diamond’s beauty. In determining the quality of the cut, the diamond grader evaluates the cutter’s skill in the fashioning of the diamond. The more precise the cut, the more captivating the diamond is to the eye.

Unlike what most people think of when talking about a diamond’s cut – it does not refer to the diamond’s shape but rather to the quality of a diamond’s angles, proportions, symmetrical facets, brilliance, fire, scintillation and finishing details.These factors directly impact a diamond’s ability to sparkle, along with its overall aesthetic appeal. How are they aligned one compared to the other? What about the size of the facets? Is the number of facets correct?  Is it shallow or deep? Is a round diamond perfectly rounded?  How the light will bounce off of it and how much brilliance and sparkle it will have.

The grades that are given are on the scale of  and are given for polish, symmetry and cut (fancy shapes don’t have cut) 

Fair/PoorRepresents roughly the top 35% of diamond cut quality. These diamonds tend to appear dull or glassy.

Good : Represents roughly the top 25% of diamond cut quality. It reflects most light that enters, but not as much as a Very Good cut grade.

Very Good : Represents roughly the top 15% of diamond cut quality. It reflects nearly as much light as the ideal cut, but for a lower price.

Excellent : represents roughly the top 3% of diamond cut quality. It reflects most light that enters the diamond. Very rare


When speaking of grading a diamond for its color the meaning is actually the diamond’s lack of color (unless speaking on fancy colored diamonds). Colors are graded on a scale of  D (colourless) to Z (light yellow or brown). D-Z diamonds are also known as white diamonds, even though most diamonds, including H colour diamonds and G colour diamonds, have varying amounts of colour.D to Z Alphabetically. D being the purest and most lucid color, completely colorless. As you go down the alphabet the diamond gets a slight tone of color, yellow or brown.
Colourless Diamonds

  • D-F Colour Diamonds (Highest Quality)

  Near Colourless Diamonds

  • G-H Colour Diamonds (Best Value)
  • I-J Colour Diamonds (Great with Yellow Gold)

K-Z Colour Diamonds (Faint to Light Colour) From K colour diamonds on, colour is visible to the naked eye. Most feel these diamonds have too much of a warm colour. K colour diamonds are usually half the price of G colour diamonds. Blue Nile does not carry K-Z colour diamonds.

J Colour Diamond (Colourless) A good value, the naked eye can’t easily detect the light yellow tone unless compared side-by-side with diamonds of I grades or higher. J colour grade diamonds pair well with yellow gold ring settings. Eight percent of customers choose a J colour diamond.

I Colour Diamond (Colourless) Still a great value, the slight yellow tint of I colour diamonds are only detected when compared side-by-side with diamonds of H grades or higher. This colour grade also pairs well with yellow gold. Fifteen percent of customers choose an I colour diamond.

H Colour Diamond (Colourless) The faint yellow hue is also difficult to detect in H colour diamonds, which are an excellent value and pair well with yellow gold settings. The colour difference between H colour diamonds and G colour diamonds is very difficult to detect unless compared side-by-side against diamonds of higher colour grades. Fifteen percent of customers choose an H colour diamond.

G Colour Diamond (Colourless) In G colour diamonds, the very slight warm and light yellow tone is difficult to detect unless compared side-by-side with diamonds of better grades. An excellent value, this colour grade pairs well with yellow gold. Eighteen percent of customers choose a G colour diamond.

F Colour Diamond (Colourless) Only a gemmologist can detect the minute colour differences between E, F, and D colour diamonds. F colour diamonds are comparable to D or E colour diamonds. The whitest of white diamonds, D-F colour diamonds, pair well with white gold or platinum settings. Twenty percent of customers choose an F colour diamond.

E Colour Diamond (Colourless) : Like D colour diamonds, Quite rare and have minute traces of colour largely unnoticeable to an untrained eye. It takes an expert gemmologist to detect the minute traces of colour in this grade. Sixteen percent of customers choose an E colour grade diamond.

D Colour Diamonds (Absolutely Colourless) : The highest grade and extremely rare—the highest colour grade that money can buy. 


A diamond clarity grade refers to the appearance of inclusions within the diamond or on it. The clarity chart goes as follows: FL, IF, VVS1, VVS2, VS1, VS2, SI1, SI2, I1, I2. Some gemological laboratories also include SI3 and I3 grading.

  • FL (Flawless) :No visible blemishes, < 1% of diamonds. Inclusions are not visible under 10X, rarest clarity grade.
  • IF (Internally Flawless) : Very slight blemishes, < 3% of diamonds. Inclusions are so small, it is difficult to see under 10x magnification.
  • VVS1 (Very, Very Slightly Included 1) : Inclusions are extremely difficult to see at 10x.
  • VVS2 (Very, Very Slightly Included 2) : Inclusions are very difficult to see at 10x.
  • VS1 (Very Slightly Included 1) : Inclusions are minor and slightly less visible at 10x.
  • VS2 (Very Slightly Included 2) : Inclusions are minor and slightly more visible at 10x.
  • SI1 (Slightly Included 1) : Inclusions are noticeable at 10X and occasionally apparent to the most discerning eye.
  • SI2 (Slightly Included 2) : More noticeable inclusions at 10X often apparent to the discerning eye.
  • I1 (Inclusions 1) : Loose diamonds of this clarity are not offered by Blue Nile, but can be found in other, pre-built diamond jewellery we sell.
  • I2 (Inclusions 2) : larity grades not carried by Blue Nile.
    Inclusions are obvious, visible to the eye under 10x magnification.

Depending on the size, location and darkness of blemishes and inclusions, these imperfections can interfere with light as it passes through the diamond. When this happens, the brilliance and beauty of the diamond is dulled, taking away from the high quality Cut.For Clarity, our primary recommendation is to ensure the diamond is eye clean, and that inclusions are not interfering with light reflection.


When people hear the term “Carat ,” they think it refers to the size of the diamond. In actuality, Carat refers to the diamond’s physical weight measured in metric carats, not how large the stone is. One carat equals 1/5 gram and is subdivided into 100 points. 

Depending on the Diamond’s Shape and how it is cut, two 1 Carat Diamonds might be quite different in size. 


To evaluate a diamond using the 4 C’s, consider the following:

  • Cut: Make Cut a primary focus during your search, as it is the “C” which most readily impacts a diamond’s beauty. Look for high levels of brilliance and fire, and be willing to reduce your spending in other areas like Clarity or Color to ensure an exceptional Cut.
  • Color: A diamond should look white or colorless to the naked eye. Ensure the Color does not distract or interfere with white and colored light reflection.
  • Clarity: Choose a diamond that is eye clean. Blemishes and inclusions should not distract from the brilliance or fire of a diamond.
  • Carat: Consider what is important for you and the one you love, but remember that brilliance and beauty will outshine mere weight each and every time. Be open to lowering your Carat weight to ensure you purchase a stunning diamond.