A Diamond Cut is basically a method, a technique or design guide used when shaping a diamond for polishing which is highly responsible for diamond’s brilliance and its superiority. Don’t misguide yourself with diamond shape and diamond cut, both are different. Hearts, Pears Oval etc are considered diamond shapes. Whereas the craftsmanship (cutting) of any shape considered as diamond cut. According to GIA, diamond cut is classified into 5 different types i.e excellent cut diamonds, very good cut diamond, good cut diamond, fair cut diamond & poor cut diamond.

The Cut of a diamond is undoubtedly a decisive factor of the 4Cs (Cut, Clarity, Color, Carat). Out of the 4 C’s, CUT has a greater influence on a diamond’s appearance and its value. A diamond’s cut grade is actually a combination of 3 different types of reflection for its overall appearance. These 3 primary aspects are distinct but have inter-related characteristics.

 Diamond Cut & Reflection

  BRILLIANCE

• Brilliance is the brightness of a diamond.
• It is created from a combination of reflected white lights through the surface of a diamond resulting in the overall brightness of the stone.

  FIRE

• Fire describes flashes of color.
• Fire is a prism effect – the light enters the diamonds and is split into a rainbow of colors which is seen through all facets of the diamond
• It is influenced by the angle of light that enters and exits the diamond and Capturing fire is one of the biggest challenges as it is harder to find it

 SCINTILLATION

• Scintillation is the sparkle of a diamond.
• It refers to the intense sparkles of light or flashes produced when moving a diamond.
• Light area and dark area is also reflected.

Diamond Cut Understanding

 Now, let’s understand the 5 Types of Cuts, graded by the GIA (Best known lab in the world)

   GIA CUT GRADE

1. Excellent Cut (EX)

• Exquisite quality cut and the highest grade in GIA system.
• Has maximum brilliance, fire, and scintillation and an even pattern of light and dark areas.
• This cut reflects all the light that enters the diamond and is considered as top cut quality diamond.

2. Very Good Cut (VG)

• Superior quality cut.
• This cut grade will reflect most of the light that enters the diamond.
• It will have higher sparkle, brilliance, and fire.

3. Good Cut (G)

• Premium quality cut.
• Reflecting most of the light entering the diamond.
• Diamonds with this grade won’t have as much brilliance and fire as higher cuts. Also, this grade diamond will be generally a bit darker or lack in scintillation.

4. Fair Cut (F)

• Adequate quality cut.
• Allows much of the light to enter the diamond and a large amount of the light will exit on the bottom or side of the diamond instead of the top.
• So Fair cut don’t have the optimum brilliance and fire.

5. Poor Cut (P)

• Inadequate quality cut.
• The majority of the light is lost through the bottom or sides of the diamond.
• This cut appears dull and deadly.
• With an obvious decrease in sparkle, even an untrained eye can see a sharp difference between this and higher cuts.

Diamond Cut Comparison

Good Cut v/s Very Good Cut v/s Excellent Cut

So, here we have very similar 3 stone from James Allen for understating the diamond cut. (left to right)

1. Good cut – 1.00 carat – K color – VS2 Clarity
2. Very Good cut – 1.00 carat – K color – VS1 Clarity
3. Excellent cut – 1.00 carat – K color – VS2 Clarity

As cutting of diamond is the main factor among 4cs of diamond. Fire, light, brilliance, luster everything depends on the diamond’s cut. In the above comparison, you can see “Good cut” diamond has low brilliance compare to “Very good cut” and “Excellent cut diamond”. Due to the proportion and symmetry of “Good cut diamond” light which reflect back on the table is less comparing to other stones.

The Diamond Cut and Light Performance

CUT is of the main factors in deciding how well the light will reflect back to the viewers. With these 3 cuts, it shows an excellent method of how light reacts in a diamond.

So, CUT is a KING. It rules everything. Therefore, the diamond cut should be your absolute top priority in choosing a diamond. It basically refers to the specific proportions of a diamond in which the light is reflected. It ultimately reflects the sparkle of the stone increasing its value and beauty.

Reference and sources

Diamonds Image source – James Allen

GIA Diamond cut education – GIA 4cs Blog

Wikipedia – Know more