The way a diamond has been cut indicates its physical shape. The cut of a diamond is the only one of the 4Cs that is not determined by nature. The intricate operation of transforming a rough stone to a uniquely cut and polished diamond is a lengthy and challenging process. Each stone has to be examined thoroughly before a skilled polisher can release the diamond’s full brilliance. Based on scientific formulas, a premium cut diamond will internally reflect light from one facet to another. A premium cut diamond will always have more sparkle than others. Diamonds that are cut either too deep or too shallow can lose light through the sides and bottom and will be less brilliant and ultimately of less value.  

Each stone loses, on average, more than half of its original weight during cutting and polishing. A typical Round Brilliant diamond has 58 facets. Polishers adhere to specific formats to bring out the best for the diamond. (See below) 

Cut also refers to the shape of a diamond whether it be round, heart, square, pear, etc. Below are examples of different diamond shaped cuts. 

The most brilliant diamonds are going to be round in shape as this relates to the symmetry and capability of the diamond to reflect nearly all the light that enters it. No round diamonds are referred to as “fancy shapes”, they have their own individual guidelines to consider for being considered well cut.


The diamond cut is perhaps the most important of the four Cs, so it is important to understand how this quality affects the properties and values of a diamond. A good cut gives a diamond its brilliance, which is the brightness that seems to come from the very heart of a diamond. The angles and finish of any diamond are what determine its ability to handle light, which leads to brilliance.
 

Disecting a Diamond

Diameter
 – The width of the diamond as measured through the girdle.
Table
 – This is the large, flat top facet of a diamond. 
Crown
 – The upper portion of a cut gemstone, above the girdle. 
Girdle
 – The narrow rim of a diamond that separates the crown from the pavilion.
    It is the largest diameter to any part of the stone. 
Pavilion
 – The lower portion of the diamond, below the girdle. It is sometimes referred to as the base. 
Culet
 – The tiny facet on the pointed bottom of the pavilion, which is the portion of a cut gem below the girdle. 
Depth
 – The height of a gemstone, from the culet to the table.