Understanding Diamond Quality

I recently got engaged to my girlfriend and have been writing a number of articles on purchasing engagement rings. When you go to purchase a ring you will most likely buy the setting and the stone separately. While there are many stones that you can have placed in your ring setting it is likely you will choose a diamond. To help you find the best value here is how to understand the quality of a diamond and what aspects are most important. Diamond quality is measured according to the 4Cs which are Color, Clarity, Cut, and Carat.


White diamonds portray a lack of color (If you choose chocolate diamonds or something similar the color scale will not apply). The ratings system runs on a scale from D all the way to Z (including all the letters in between). There are a five categories of diamond color within this scale: Colorless (D,E, F), Near Colorless (G, H, I, J), Faint Yellow (K,L, M), Very Light Yellow (N, O, P, Q, R) and Light yellow (S-Z).

If you are looking for a diamond beautiful to the naked eye (doubtful that your girlfriend will whip out a loupe to inspect it) you should look for a diamond D-H. Colorless diamonds (D,E,F) are very high quality but also come with a very large price tag. G and H graded diamonds contain so little color that is barely noticeable to the naked eye. I and J graded diamonds have a slight amount of color that is noticeable to the naked eye. Anything beyond J should probably be avoided as there will be noticeable color especially in smaller diamonds.


Diamond clarity grades the lack of inclusions or blemishes. Internal characteristics of the diamond are inclusions while external characteristics are blemishes. The clarity rating is given based on the number, size, nature, relief, and position of these inclusions or blemishes. While it is not necessary to understand exactly how the diamond is graded it is important to understand what the grade signifies. None of these characteristics are obvious to the naked eye but may affect diamond brilliance. Have the jeweler let you see the diamond magnified to judge the size of possible inclusions or blemishes.

There are six grades or categories that a diamond may fall under. Flawless (FL) means there are no inclusions or blemishes visible under 10x magnification (these diamonds can be very pricy). Internally Flawless (IF) means that there are no inclusions visible under 10x magnification although there may be blemishes. Very, Very Slightly Included (VVS1 and VVS2) means that there are inclusions so slight they are difficult for a skilled grader to see under 10X magnification. Very Slight Included (VS1 and VS2) are observed with effort under 10X magnification, but are minor. Slight Included (Sl1 and Sl2) have inclusions are noticeable under 10x magnification. Finally, Included (I1, I2, I3) have inclusions obvious under 10x magnification.


The cut of the stone is crucial to the stone’s beauty and sparkle. While diamonds do come in different shapes the cut refers to the workmanship of cutting the diamond to allow the diamond facets to interact with light. Different jewelers may use their own grading system to measure the quality of cut but there are different proportions of a diamond’s cut. While it is not necessary to go into every portion of a diamond cut it is important to understand the three effects the cut may have on light. The cut will determine the proportions of the diamond.

Diamonds that are too shallow (larger surface area and shallow depth) will have light travel straight through the diamond without reflection. If the diamond is conversely too deep the light will enter the diamond and then be refracted to the side out of the bottom of the stone. The ideal diamond will reflect the light entering the stone back up to your eye. Ideal diamonds have an equal mix of light and dark portions when looked straight down on the diamond. Poorer diamonds will be either very dark or a bland light color.


The easiest to understand carat simply refers to the weight of the stone. Each carat can be subdivided into 100 points. Each point matches up to the hundredth of the decimal. A diamond .35 carat diamond is a thirty-five pointer. Not surprisingly larger diamonds are more rare and more valuable. A note to make is that carat weights that are exactly the following (.5 carat, 1 carat, 1.5 carat, 2 carat, etc.) can be very expensive. However, if you have carat weight that is slightly off one of these exact measurements the diamond will be much cheaper. If you are worried more about the size of the stone you can search for stones based on top surface area measured in millimeters, (but remember having a shallow or deep diamond will affect the brilliance of the diamond).

The Price

I have listed no prices in each of the 4C’s because of variability. Your diamond price will change depending on the grades you select for each of the 4 C’s. Determine what is most important to you and make sacrifices accordingly. If you want a beautiful diamond you may end up choosing something small. If size matters remember the diamond may not shine as you hoped. The diamond does represent a large investment so look into insuring the diamond at the jeweler or including it as part of your home insurance, good hunting!