Diamond Ratings

Diamond Ratings

February 28, 2020

Anyone who has shopped for a diamond ring before understands that not all diamonds are created equal. In fact, every diamond is unique and has its own rating. Learning about the diamond ratings ⁠— often referred to as the four C's ⁠— can help you determine what factors you should focus on to best utilize your budget. Continue reading for an in-depth look at the diamond ratings and which are most important.

What Are Diamond Ratings?

Image via Flickr by Neil Rickards

Diamond ratings are the grading system that professionals use in the diamond industry. This system established the use of four different factors to describe and classify diamonds: Cut, Carat, Color, and Clarity.


Cut refers specifically to the angles, proportions, brilliance, scintillation, symmetrical facets, and finishing details. The diamond's proportions determine how the light performs when it enters the diamond. If light enters through the crown and exits through the pavilion, for example, the diamond will appear dark. Diamonds with a good polish and different proportions will make the best use of light and will be bright and colorful.

A diamond has the appearance it does because of three optical effects: white light reflections referred to as brightness, the areas of light and dark called scintillation, and the flashes of color called fire. A diamond's pattern is the size, arrangement, and contrast of bright and dark areas. The pattern should have a sharp, crisp look.

These are all factors that contribute to a diamond's aesthetic appeal, allowing it to sparkle. The Gemological Institute of America (GIA) grades a diamond's cut on a scale of Ideal, Excellent, Very Good, Good, Fair, and Poor. A diamond that has an ideal or excellent grade signifies that its angles and proportions are cut for maximum brilliance. 

The term "cut" can also refer to the shape a diamond has been fashioned into.

The most common cuts are:

  • Round brilliant: This is the most popular shape for a diamond but also tends to be the most expensive.
  • Princess: This square-shaped diamond is the second-most popular cut and provides a contemporary look that many consumers prefer.
  • Marquis: This shape resembles a football and tends to be slimming on the finger.
  • Pear: This diamond is shaped in the profile of a pear.
  • Emerald: This cut is rectangular and gets its name from the ⁠— also rectangular ⁠— shape of the emerald gemstone.


A Carat refers to a diamond's weight, which isn't necessarily representative of size. For example, two diamonds could have the same weight but, because of differences in shape and cut, be quite different in size. 


A diamond's color rating is determined by how white or colorless it is. A diamond's color is graded from D to Z, with D being the most colorless and Z having the greatest amount of yellow or brown. A diamond's color grade can have a significant impact on the price. The most critical aspect of color is making sure your diamond appears colorless in relation to its setting. While you do want to ensure that your diamond appears colorless in the setting, you also want to avoid overpaying for a color rating that's too high.


Clarity is the rating that assesses small imperfections on a diamond's surface and within the stone. Imperfections on the surface are called blemishes, while internal blemishes are known as inclusions. Diamonds with the fewest and smallest number of inclusions have the highest clarity grades. That said, gemologists typically use the term "internal characteristics" to describe inclusions rather than flaws. That's because the inclusions are typically what gives a diamond its character. Keep this ⁠—  and the fact that most inclusions aren't visible to the naked eye ⁠— in mind when you're looking for a diamond.

Clarity is graded on the following scale:

  • Flawless (FL) Diamonds
  • Internally Flawless (IF) Diamonds
  • Very, Very Slightly Included (VVS) Diamonds
  • Very Slightly Included (VS) Diamonds
  • Slightly Included (SI) Diamonds
  • Included Diamonds

For clarity, the primary recommendation is to ensure that inclusions are night interfering with the light as it passes through the diamond.

Why Do Diamond Ratings Matter?

The four Cs help determine a diamond's value and indicate quality. Diamond sellers often use diamond ratings to set their pricing. That said, the most important consideration is how attractive the diamond is, overall, to the naked eye. It's important to find the right balance between the four C's in order to spend your budget on the components that will be most apparent. 

How Diamond Ratings Affect the Cost of a Diamond

The higher a diamond registers on the rating scales, the most expensive it will be. This is simply because diamonds that are highly rated are also the rarest, and the rarer a stone, the higher the demand and, ultimately, price.

Most Important Ratings When Selecting a Diamond

Each of the four C's contributes to a diamond's overall beauty, making each stone unique. That said, some of the ratings are more important than others. If you are purchasing a diamond, you should consider:

  1. Cut: This should be the main focus of your diamond selection, as even a beautiful two-Carat diamond can be dull if not cut exceptionally well. A diamond's cut is the most significant indicator of beauty and is more important than any of the other diamond ratings. 
  2. Color: This is the second most important rating, as a diamond should appear colorless to the naked eye.
  3. Clarity: This should be your third consideration. Your diamond should be eye clean and free of blemishes and inclusions that distract from the stone's brilliance.
  4. Carat: While the weight of the stone is an important consideration, it shouldn't be your greatest focus. For example, you may want to consider lowering your Carat weight to purchase an exceptionally cut diamond.

Now that you have a better understanding of the most important factors when shopping for diamonds, you should feel more confident when shopping for your next diamond. Confidence, the fifth C, is important when you are choosing a diamond that will be in your possession for decades to come. Shop with confidence when you buy your diamond through Unique Gold and Diamonds. We offer a large selection of exquisite diamond engagement rings and diamond statement rings. Browse our collection today!