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Diamond Cut

Diamond cut is the most important aspect when it comes to choosing a diamond as it dictates the sparkle and brilliance of a diamond. Yes, as you know, a diamond that is extracted from the earth’s surface comes in a rough and natural form. These diamonds are then cut by skilled diamond cutters who look to generate the maximum sparkle from the given rough diamond. In the process, variable types of diamonds and diamond shapes are derived, depending on the size and texture of the rough diamond. 

This is how the diamond gets facets and faces on its surface that have the ability to bounce and reflect light. The overall sparkle and shine of the diamond thus depend on the number of facets, angles, and the way in which the diamond is cut. A more detailed overview of the way in which a diamond generates the sparkle and shine can be seen when we study these two factors.

  • Refractive index of a diamond

It is this stunning physical characteristic of a diamond that makes it stand apart from the other gems. The refractive index (RI) of a diamond is an outstanding 2.417, which is very high when compared to other gems. The amount of incident light that is reflected back to the viewers depends on the RI of a diamond. That is why diamond cutters make it their responsibility to cut the diamond in such a way that the refractive index is maintained. This indeed results in different types of diamond shapes and diamond cuts, resulting in quality diamonds. 

  • Dispersive power of a diamond

You probably have heard of terms like the hall of mirror effect. You’ve also heard jewelers and local jewelry stores talking about terms like the fire and characteristic brilliance of the diamond. Well, what does this really mean?

Yes, they are talking about the dispersive power of a diamond.  As we all know, a white prism can split light into its constituent colors.  Then you can just imagine how profoundly a well-cut diamond can split light. According to the diamond cut, different diamond shapes split white light variably. These flashes of light are the so perceived character and brilliance or fire of a diamond that we so popularly hold on to.

Anatomy of a diamond

In order to fully understand the concept of diamond cuts, you must first understand the anatomy of a diamond. A diamond consists of several parts, which individually have to be perfectly cut and polished to acquire the perfect diamond. Accordingly, a diamond’s cut is graded and you can check for individual parts that stand out and those that are flawed. 

 Yes, and that takes us to the parts of a diamond.

Anatomy of a diamond

1.  Table of a diamond

This is the part of a diamond that solemnly generates so much attention. The table of the diamond is the top-most facet that is seen when viewed from the top. It is through this surface that light enters the diamond and hence penetrates through the inner surface,  creating the fire and sparkle that we see in a diamond. According to the size of the table, a diamond appears to be larger or smaller. 

Table percentage of a diamond

The table percentage of a diamond will help you differentiate between two diamonds that have the same cut but differ in their table sizes. It is an important component of a diamond’s overall cut grade. This way you can select the better diamond out of the multiple options. 

The table percentage of a diamond tells you how wide a diamond’s table is compared to the overall width of the entire diamond. As you see it depends on the shape of the particular diamond. Different types of diamonds and diamond shapes will have different table percentages. 

The most popular of all, the round diamond should have an ideal table percentage of somewhere between 54-59%. Whereas a princess cut diamond should ideally have a table percentage of 66-75%. 

However, when going for the right diamond cut,  you don’t necessarily have to look for the table percentage. But do so if you have two diamonds having the same cut grade. 

2. Depth of a diamond 

When considering the diamond cut, the depth of a diamond is a crucial factor. The depth of a diamond is the distance between the topmost facet of a diamond(table) and the culet of a diamond.

It determines how much light is reflected from the facets of the diamond back to the observer’s eye. This is why you need to take a look at a diamond’s depth, as it really influences the quality of the diamond you get. The diamond’s depth shouldn’t be too shallow or too deep.  This might result in insufficient amount of light being scattered through the interior facets, thereby reducing the sparkle of the diamond.

For instance, a diamond’s depth which is too deep results in the incident light being reflected off the first pavilion facet.  This causes the reflected light to strike the second pavilion at a very low angle causing the light to escape through the bottom surface of the diamond. 

The ideal depth of a diamond will depend on the diamond cut and diamond shapes. The ideal depth percentage differs for different types of diamonds. If you are looking to buy a round diamond, then the ideal depth percentage is between 59 and 62.6 percentage.  Diamonds of these depths are such a sensation to the eye, the sparkle and brilliance of such diamonds being exorbitant. The ideal depth percentage of a princess cut diamond lies between 68 to 75%.  The death percentage for a cushion cut diamond lies between 61 and 68 %.

3. Crown of a diamond

The crown of a diamond is what it actually says.  It is the part of the diamond above the girdle that resembles the shape of a crown. The way in which a diamond crown is cut dictates the amount of light that enters the diamond and escapes from it. Yes, it is equally or even more important than a diamond’s depth or table, when it comes to the amount of light and sparkle that a diamond derives. By looking at the crown angle, you can determine whether a diamond is of a quality cut grade or not. The Crown angle shouldn’t be too heavy or steep. It should be cut in perfect proportions so that the diamond yields the maximum sparkle. Even though the ground angle does not need to be as precise as the pavilion angle, a round diamond having a crown angle between 30 to 35 degrees is the ideal one. 

4. Girdle of a diamond

Have you heard of the Fish eye effect? It might sound great but not when you see that your diamond loses its sparkle because of this.  Yes, and this is because the diamond girdle reflection in the pavilion of the stone reflects back to you. 

When viewed from the top, a diamond’s girdle is the portion that creates the outline. It can also be seen as the separation between the table and the pavilion. A diamond’s girdle won’t qualitatively affect the overall diamond cut. All you have to do is look out for diamonds that have good girdle thickness existing between the range “very thin” and “very thick.” 

Make sure that the overall cut grade of the Diamond, comprising the diamond depth and the table is of proper proportions. This way, the girdle’s reflections won’t affect the diamond shine, thus creating the ambiance for the perfect diamond. Modern diamonds have faceted and polished girdles that frame the outlook of an elegant diamond.

5. Pavilion of diamond 

The crown and pavilion of a diamond interchangeably play a great role in extracting the right amount of light to your eyes.  The pavilion of a diamond is that portion of the diamond that appears below the girdle. It is the bottom-most part of the diamond that looks tall and elegant. When looking into the overall cut grade, the diamond’s pavilion must also be considered as it is very important when it comes to refracting light. Light that enters the diamond through the crown is reflected back to the pavilion and hence to your eyes. For a round diamond, the ideal pavilion angle lies between 40 – 41.6 degrees.

6. Culet of a diamond

This is the part of the diamond that is most often graded as ‘none.’  It is the bottom-most point of the diamond which is the thinnest part of the Diamond. When considering the overall cut grade of a diamond you don’t have to be bothered about evaluating its culet. As most cutlets are evenly shaped and cut so that light does not reflect or escape from this part of the diamond. A diamond with an above-average culet size will tend to leak light. Always make it a point to consider buying the right sized diamond. 

Overall cut grade of diamond

To make life easier for you, the GIA (Gemological Institute of America) follows a policy where they evaluate the overall cut grade of the diamond. All you have to do is look for the certification of the appropriate diamond that you are going to buy to give you an idea of the quality cut grade of it. The GIA grades the diamond cuts based on the sizes and angles of the facets of a diamond. All internal factors of a diamond such as its table percentage, depth, girdle, pavilion, crown, and culet are evaluated when determining the overall cut grade of the diamond.

The Diamond cut scale

According to the light performance and sparkle of a diamond, the GIA classifies diamond cuts typically into four.

They are:

1. Fair and poor

The diamonds that are graded fair and poor are those that render a poor sparkle. They do not yield the optimum amount of light since light leaks from their surfaces as a result of its interior structure. So don’t consider buying a fair or poor graded diamond if you are looking for that sparkle. 

2. Good 

The diamond cuts that fit into the diamond chart of ‘good’ are those diamonds that exhibit the ideal diamond qualities. They render the optimum amount of sparkle and brilliance. The facets and faces of these diamonds are cut in such a way that light reflexes and bounces off its surface qualitatively. Good cut diamonds effectively raise the quality of diamonds depending on the diamond shapes and types of diamonds. 

3. Very good

The diamonds which are graded as ‘very good’ are those that absorb and emit the sparkle of a diamond in the most exorbitant fashion.  These Diamonds are cut to achieve such perfection when it comes to the fire and brilliance of diamonds. The facets are cut in such a way that almost 99 % of the light is reflected and absorbed in its surfaces,  offering a great visual appeal to anybody looking at it. Only the top 15 % of quality diamonds are graded as very good. 

4. Excellent

These diamonds take hold of the top positions when it comes to the best-cut diamonds in the world. These diamonds are very expensive and require millions of dollars to own them. The Diamond cutters who cut and shape these types of diamonds put in all their focus and energy to craft such explicit beauties. These diamond cuts render the utmost sparkle and character of diamond. You will find these diamonds enlisted in the top 3 % of all diamonds. The rise in technology has given way for more and more excellent grade diamonds to come into the picture. 

Typically two cuts of diamonds

When it comes to evaluating the diamond and different Diamond shapes,  we use two prominent terminologies to differentiate the different Diamond shapes  and cut.

The first one being the step cut is the modern version of a diamond cut where the facets are shaped in such a way that they look like a series of steps. A diamond is cut in such a way so that it renders the maximum brilliance and character of a diamond.  These cuts are prominently found in the emerald cut diamonds that you find in the market today. A step cut diamond can vary in terms of the diamond sparkle and the type of brilliance rendered when compared to that of a brilliant cut diamond. 

The second category of diamond cuts which comes under the brilliant cut, is the most popularly known diamond cut. They are the famous round cut diamonds and the princess cut diamonds that we all know of.  These diamonds exhibit maximum sparkle as they have more number of facets that are tuned to reflect and bounce back maximum light. 

Polish and symmetry of a diamond

When considering the overall cut grade of a diamond, you also have to look into the polish and symmetry factors of a diamond. The polish of a diamond is basically how smooth and how reflective the facets of a diamond are. A diamond which has a quality cut should be well polished so that optimum light is reflected from its facets.  The other factor which is symmetry is simply the way in which the facets are distributed over the entire diamond. That is why the symmetry of a diamond will determine the quality cut grade. So make sure to look into these two factors when you consider the diamond cut.