"Cut" can have two meanings as it relates to a diamond. It can mean the shape the diamond is cut to, for example a princess cut (square cut), or, it can mean the quality of cut of a diamond. We will be referring to the quality of cut.

Arguably the most desirable of the 4 C’s is cut. It is important to understand how a well-cut diamond compares to a poorly cut diamond in appearance as well as its value. Why is it more valuable? Here are four reasons:

  1. More of the rough diamond is wasted in obtaining a well-cut diamond.
  2. It takes a great deal of knowledge, expertise, and experience to be a great cutter. Few cutters in the world can create an Ideal Cut.
  3. Less than 3% of diamonds achieve an Ideal Cut, thus making them very rare.
  4. Many people agree an Ideal Cut/Very good cut is the most sought after aspect of a diamond, making it a characteristinc in high demand when searching for a diamond.

 



     
 
     
 


A round diamond cut to precise proportions and symmetry can show a "Hearts and Arrows" pattern when viewed with a proportion scope. These diamonds arguably give the most "fire" and "brilliance" than any other.

 
 
     

Essentially, the better the cut the more brilliance and scintillation (sparkle and fire) a diamond will have. If a diamond’s depth or diameter is greater than it should be, light will escape through the pavilion and not be reflected back to the observer’s eyes. The same holds true if a diamond’s diameter is less then it should be (which is common for larger diamonds in many chain stores). This is simply done to obtain a heavier weight--the quality of cut is sacrificed to obtain a larger carat size. However, bigger is not always better. Most people will choose to sacrifice weight to get a very good/ideal cut diamond when they have a chance to compare. As you can see below, if the diamonds are cut too shallow or deep, light will enter through the top and escape out the bottom.

Polish and symmetry are two important factors in determining the cut. These two characteristics are easily viewed on reputable gem lab certificates. "Polish" refers to the smoothness of the diamond facets. With poor polish, the diamond may appear dulled or cloudy-like. "Symmetry" refers to the alignment of facets. If the symmetry is poor, light will be misdirected when it enters and exits the diamond. Below is a picture of poor symmetry on the left, and excellent symmetry on the right.

 

 

Another key factor in choosing a well-cut stone are the existing proportions of the diamond. Below is a picture of a diamond and a graph showing some key information on what to look for when ldentifying good proportions. 2006 has been an exciting year with the GIA introducing a cut grade on their reports. Although the Gemological Institute of America maintains their theology that an ideal cut does not exist, the AGS have narrowed down what proportions seem to appear to have the most sparkle and fire according to instruments and light measuring devices. Yet after thousands of tests, the GIA has noticed that here are a number of different combinations that appear to bring forth a lot of sparkle and fire. The main way GIA grades the cut is the actual appearance to the eye as compared to AGS with intruments. Infact....we know of a company which has shown thier customers an AGS ideal vs. a GIA excellent. To thiers and our suprise the customers overwhelmingly chose the GIA excellent over the AGS ideal cut for the overall appearance of the diamond (scintillation, fire, brilliance, etc) Having said that, in our opinion both are equally desireable and display incredible sparkle. Please note that the information listed below will narrow down what to look for in terms of proportions, but it is only for your information. It is best to see the diamond for yourself and compare.

 

The chart below is for round diamonds only.

Ideal Cut (AGS best)

Excellent (GIA best)

Very Good

Good

Medium/Fair

Table %

53%-57%

53%-60%

53%-62%

53%-65%

53%-<65%

Depth %

59%-62.7%

59%-62.9%

58.1%-63.5%

56.1%-64.3%

56%-<64%

Polish

Excellent - Very Good

Excellent- Very Good

Excellent-Good

Excellent-Good

Very good-Poor

Symmetry

Excellent-Very Good

Excellent-Very Good

Excellent-Good

Excellent-Good

Very good-Poor

Girdle

Thin-Slightly Thick

Thin-Slightly Thick

Very Thin-Thick

Very Thin-Very Thick

Extremely Thin-Extremely Thick

Culet

None-Medium

None-Medium

None-Medium

None-Large

None-Large

Crown %

14.4-%-16.2%

12%-16.3%

10.5%-17%

9%-<17%

8%-<17%

 

For most people, cut is more important than the color, clarity, and carat size when selecting a diamond. The cost between a medium cut and an ideal cut can be up to a 45% difference. Is it worth it? You will have to decide the answer to this question. It is essential to view diamonds for yourself and compare them to determine what characteristics your perfect diamond will have. It is possible to buy a very nice diamond, the cut being good or very good, which will have lots of sparkle and cost considerably less than an ideal cut. In this case, you can of course buy a bigger diamond. If size is not a a major factor in your search, than we reccomend choosing an Ideal or very good cut. You can expect to see up to a 10% increase in value, as each class of cut gets better because of it’s rarity.