Diamond Quality Rating & The 4Cs

Diamond quality rating is all about the 4Cs. A diamond’s 4Cs give you the information you need to compare the characteristics and quality of one diamond to another. Below you’ll find our easy-to-understand guide on the 4Cs and tips on saving money on an engagement ring.

Large diamond held with a caliper

The 4Cs are a rating system that the GIA (Gem Institute of America) established in order to assess the level of quality for each of the 4 most important attributes of a diamond: CUT, CLARITY, COLOR, AND CARAT.

GIA doesn’t set pricing for diamonds. Instead it educates consumers on diamond quality through the 4C ratings and helps take the guesswork out of buying a diamond. The 4Cs are used the world over—so learn them, live them, love them!

Cut: Diamond Quality Rating 1 of 4

A diamond’s cut is probably the most important attribute of all 4. People confuse diamond cuts with diamond shapes. But a diamond cut refers to a diamond’s proportion and how it’s faceted, which results in its brilliance and sparkle. The shape is the form of the stone.

The facets (flat surfaces) of the diamond are cut to make the best use of light. It’s a diamond’s cut that gives it that gorgeous sparkle and dictates how light enters and exists the diamond.

A diamond cut has three qualities assigned to it:

  1. brilliance | which measures the light reflected from a diamond
  2. fire | the way light disperses into the colors of the spectrum
  3. sparkle |  the little flashes and glimmers you see when the diamond moves & catches light

To appreciate the quality of a cut we need to understand the anatomy of a cut diamond:

Diagram of the parts and names of a diamond

The table is the flat top of the diamond which is part of the crown. The girdle is the ‘ridge’ where the angle changes on the cut and the pavilion starts. At the bottom is the culet.

Types of Diamond Cuts

In the illustration below you can see how light is reflected from a diamond and how the facets and proportions of the cut affect the results.

Different illustrations of an ideal, shallow and deep diamond cut

Ideal cut diamonds  | As the name implies, this is the ideal cut to allow light to reflect back up through the crown. It has the correct proportions to create awe-inspiring brilliance and sparkle.

Fine cut diamonds | These are cut well but are not quite Ideal. They’re a great money saving option with much of the light still being reflected properly. With Fine cut diamonds you reduce the cost of the diamond without having to sacrifice much in the way of cut quality.

Shallow cut diamonds | The pavilion (the bottom part of the diamond) is not long enough in this case. This cut will decrease the brilliance of the diamond, since light is getting lost through the bottom instead of being reflected back out through the top.

Deep cut diamonds | The opposite of shallow cut, here the pavilion is too long. Light will escape through the sides of the diamond, reducing the desired sparkle.

Clarity: Diamond Quality Rating 2 of 4

Diamond clarity is about flaws and inclusions in the stone.  Any imperfection inside a diamond is called an inclusion, these are created when the diamond was forming. Imperfections on the outside of a diamond are called flaws. The fewer the imperfections, the rarer and more valuable the diamond.

Cutters try to remove as many flaws as possible, but inclusions cannot be removed since they are on the inside of the stone and are invisible to the naked eye.

The issue with inclusions is that they limit the ability of light to pass through a diamond. Since diamonds are formed within the earth under intense pressure, imperfections are likely to occur. Most diamonds have a flaw of some sort—it’s rare to find one without any.

Think of them as a beauty spot. They bring character and can make a diamond uniquely beautiful (like Cindy Crawford’s facial beauty mark).

Diamond Clarity Chart

The rating system for diamonds, when it comes to clarity, ranges from flawless to imperfect. Flawless diamonds are very rare, even most jewelers haven’t ever seen one.

A diamond clarity chart ranging from flawless to imperfect

As you progress from left to right on the diamond color clarity scale you begin to see more inclusions. Remember that we are looking at these stones through 10X magnification and these would not be visible to the naked eye.

Anything from VS-1/VS-2 left, are really minor imperfections. From that point on, the further you go to the right on the diamond clarity chart the more likely that the imperfections may start affecting the brilliance and transparency. In layman’s terms this means less bling! However, not all inclusions are equal and some will have much less of an effect than others.

Color: Diamond Quality Rating 3 of 4

Diamond color actually refers to the absence of color. Diamond color and clarity is really about what is NOT there. The less color the more valuable the stone.

Of course we’ve all heard of pink, or Canary yellow diamonds which are considered fancy-color diamonds not white diamonds. They sit outside of the color range we’re discussing here and are not included in the standard color chart.

Fancy-color diamonds are very rare and very pricey and unlike white diamonds are judged on the intensity of color rather than the absence of color.

For white diamonds, the ideal is for them to be entirely colorless. They reflect the most light and therefore have the best brilliance and shine.

Diamond color scale D-Z

The diamond color grade scale starts at colorless ‘D’ and runs through to ‘Z’ which has the most presence of color. So just remember the following when evaluating diamond color:

D E F = Colorless

G H I J = Near Colorless

K L M = Faint Color

N O P Q R = Very Light Color

S T U V W X Y Z = Light Color

A jump from one letter to the next (even within a grade) can mean a difference of thousands of dollars and reflects on the ‘quality’ of the stone. The ‘theory’ behind diamond color is that the more color in a diamond, the less it will shine.

Carat: Diamond Quality Rating 4 of 4

1,2,3,4,5 Carat Diamonds—What’s It All About? Carats (Cts) are a measure of weight for diamonds.  A carat is made up of a 100 points just like a 100 pennies equals a dollar.  So, 100 points = 1 carat =  0.20 grams.

Because diamonds are so rare, the bigger the carat size, the bigger the weight, the bigger the price tag. Which means a 2 carat diamond is worth more than two 1 carat diamonds even though the total weight is the same. You’ll also pay a lot more for round numbers like 1, 2 or 3 carats. If you find a diamond that is just shy of these numbers, you can save significantly.

Diamonds ranging from .5 carat to 5 carats

Remember that carat is only one of the 4Cs described here, and bigger does not always mean better.

A 2 carat diamond that’s cut poorly is not nearly as beautiful as a smaller diamond, cut by a skillfully. And, even if it’s cut well, it may have poor color and clarity.

Lots of folks go into jewelry stores and immediately gravitate towards the larger diamonds. Stores actually put out inferior quality diamonds in higher carat sizes. They know that many will only think in terms of carats and size and not think about all the other quality components of a diamond.

Diamond Quality Ratings, The 4Cs & Saving Money

No.1 | Size Does Matter

Round number diamonds like a 1/2 carat, 1 carat, or 3 carat diamonds have an added premium just because they are round numbers.

Our first tip… knock of a tenth of a carat for diamonds around 1 carat in size or larger. You’ll notice the tenth of a carat difference in smaller diamonds but not when you hit 1 carat or more.  The diamond below on the left is .90 carats, the one on the right measures 1 carat. The visual difference is small but the value difference can be huge with savings can run into thousands of dollars.

1 carat round diamond compared to a .9 carat diamond
The same is true with smaller diamonds. If you’re looking at a .25 carat stone, compare it to a .23 or .27. You’ll be surprised by how much money you save just because it can’t be called a “1/4 carat”.  As crazy as it sounds, even a diamond that is a little larger can be less expensive than one that is a perfectly even number.

No.2 |  Be a Little Color Blind

The color (or lack thereof) of a diamond can have a significant impact on its price. So if you’re looking for ways to save money go with the lowest color rating you can get away with. In the “colorless” diamond group, the ratings run from “D” through to “J”. D, E, and F are the most expensive while G, H, I and J are considered near colorless.

Diamond color grades

To the naked eye, they’ll all pretty much look the same and the difference in cost is based on the rarity of D (or the higher grades) rather than them being more beautiful. So, go with the second group and save more than a few bucks. Keep in mind, if you go below an “I” grade the stone will look ‘whiter’ if you set it in yellow gold.  Against white metals like white gold and platinum, you may notice the color more.

No.3 | Setting The Scene

If you want to save money but are concerned about sacrificing “Bling!” then choose a setting that’ll make your diamond look bigger. Bezel settings and Halo settings are perfect for this.

A Bezel setting frames the diamond in metal, it’s great for protecting the stone from chips and damage and makes the stone look bigger. A Halo setting also frames the stone but this time with small diamonds or diamond chips.

Bezel and Halo Settings for diamond engagement rings

The diamond rings above all come from JamesAllen. See how the halo and bezel work to make the center stone look bigger? It’s a great trick that fools the eye and save you dollars.

Again, make sure that the setting is platinum or white gold so that the diamond blends in with the metal color. Your diamond will look so much bigger than it really is and you’ll get the most “Bling” for your buck!

More on the 4Cs Straight From the GIA

If you want to understand more about the GIA and its diamond quality rating system, check out the video below.

For privacy reasons YouTube needs your permission to be loaded. For more details, please see our Privacy Policy.
I Accept

Don’t get carried away with GIA’s diamond quality rating scale. It’s only there to help standardize diamond ratings so that you can understand why one stone is worth more than the other. Each diamond has its own beauty which makes it unique and you can’t put that on a rating scale.