THE 4 C’s


 The four categories that we use to evaluate the price of a diamond are known as the 4 C’s. 




“How many carats?” or “How big is it?” are usually the questions people ask about a diamond, especially engagement rings.  Carat is the measurement of diamond weight and is often confused with the size. 


A bigger diamond is not always the best advice when selecting a diamond, since there are many other factors that are equally important.  A stone may weigh more in carats but look smaller than it should, an illusion caused by the cut of the stone.  For example, a properly cut round brilliant diamond that weighs one carat should be approximately 6.5 mm across.  However, a stone weighing much less than that could be cut too shallow to make it appear as large as the properly-proportioned stone. Some jewelers may try to put a higher price on this stone, because it appears to be larger than it really is.  The opposite can also occur when a stone is cut too deeply, but weighs the same as a properly cut stone.  In both cases, the poorly cut stones cost the jeweler less, but are sometimes not discounted to the public accordingly.


This is a very good reason to always buy certified stones graded by independent laboratories. The stone is evaluated by a third party that is not financially invested in the quality or size of the stone. This means you get an unbiased evaluation.


There are certain points as a diamond's size increases where the price jumps even more. For example, going up two to four points doesn't usually have a great impact on the price of a diamond. However, if that increase crosses size categories, the price will change dramatically.  Also, diamonds weighing in the oversize range may trade at 5%-10% premiums over similar quality straight sizes.  Below you will find the size categories and oversize ranges.



Size Category OversizeRange
0.50 – 0.69 0.60 – 0.69
0.70 – 0.89 0.80 – 0.89
0.90 – 0.99 0.96 – 0.99
1.00 – 1.49 1.30 – 1.49
1.50 – 1.99 1.75 – 1.99
2.00 – 2.99 2.50+
3.00 – 3.99 3.50+





The number, size, type and location of imperfections in a diamond determine its clarity. These imperfections come in many forms: black piques, feathers and clouds to name a few. Below is the rating system used for diamond clarity:



Flawless, Internally Flawless


Very, Very Slightly Included (1, 2)


Very Slightly Included (1, 2)

SI Slightly Included (1, 2)
I Included (1, 2, 3)




The importance of clarity, as with all of the four C's, is subjective. Some people value clarity over color or carat, while others may put carat above anything else. It all comes down to individual preference.

 The non-subjective importance of clarity lies in whether the imperfections affect the appearance of the stone. Diamonds with a clarity grade of VS and above are not greatly affected by the imperfections because they can only be seen with magnification. Imperfections do not affect the "sparkle" of a diamond unless they are large enough to obstruct light within the stone.




Letters are used to grade the color of diamonds. The letter D is used as the highest or whitest rating. As you move down through the alphabet, the color becomes darker, moving to yellow.



The Gemological Institute of America has provided the industry with the most comprehensive system for evaluating the different color grades. Those colors range from D-Z in the alphabet and then move into the "fancy yellow" grades.




GIA Grade Description 

  GIA Grade Desciption


 D - F

G – J 

K – M 

N – R 

 S – Z






Very Faint






Cut is perhaps the most important of the four C's.  It is the cut of a diamond that releases its brilliance. A well-cut H, SI stone will look better than a poorly cut E, VVS stone when they are placed together. The facets are what create the sparkle and scintillation of a diamond.


Just as color and clarity have a grading system, so does cut.  In 1919, Marcel Tolkowsky calculated proportions that have become the benchmark for cutting round, brilliant diamonds called the "Ideal Cut" or "American Cut Ideal Brilliant."

 The most widely recognized grading laboratories have developed their own terminologies in evaluating cut. Some are:  excellent ideal cut, Tolkowsky ideal cut, AGS 000 and premium cut.  All of these terms represent proportions ranging from poor to fair to good to very good to excellent.



THE IDEAL CUT       When a round brilliant diamond has been cut to “Ideal” proportions by a master cutter, it is a splendor to behold.     The Ideal Cut Diamond describes a round brilliant diamond that has been cut to exact and mathematically proven proportions.  Its symmetry, with 58 exactly placed facets, produces the ultimate in luster and beauty.

     When a diamond is cut to the ideal proportions, all of the light entering from any direction is totally reflected through the top and is dispersed into a display of sparkling flashes and rainbow colors.

 The Ideal Cut


PREMIUM CUT      A Premium Cut diamond demonstrates subtle variations from the Ideal Cut.  Although dimensional differences affect a diamond’s reflection of light, a Premium Cut still achieves a harmonious balance between it’s proportions and the display of brilliance.   







 Proportions of the Premium Cut




Light* entering the diamond reflects internally from facet to facet and is reflected back through the top ONLY, creating maximum brilliance. 

 The Ideal Cut 



Most diamonds are “spread” in their cutting to retain maximum weight from the original rough.  A heavier diamond will result, but at a dramatic sacrifice of potential fire and brilliance.




When a diamond is cut too deep, light* leaks out of the bottom, brilliance is lost and the center of the diamond will appear to be dark. 

  Too Deep


When a diamond is cut too shallow, light* leaks out of the bottom, brilliance is lost and the diamond appears watery, glassy, and dark.

  Too Shallow


* Arrows on the diagram simulate the flow of light in the diamond.