Cut

Cut is the human contribution to a diamond's beauty, brilliance and fire. The way a diamond is cut can affect all of the other C's. A well-cut diamond will allow light to enter the stone, bounce off the internal facets and be reflected back through the top, creating the brilliance and fire only a diamond can. Diamonds can be cut to virtually any shape and size. Some popular diamond cuts include round, oval, marquise, pear, heart, emerald, princess and radiant. There is no doubt that round brilliant is the most popular cut today.

Today's designs are the result of hundreds of years of experience. Already in the 1920's a Russian mathematician by the name of Marcel Tolkowsky calculated the proportions of the facets in a round diamond that would bring an ideal balance between brilliance and dispersion. Any deviation from these designs will compromise the beauty of the stone.

When cutting a diamond cutters have to choose between optimizing weight (weight equals money) or optimizing beauty. Sadly, many cutters sacrifice beauty rather than weight. They can get away with this only because stores have been keeping customers in the dark and pushing weight rather than beautiful proportions. It is easier to convince someone to buy a bigger diamond than a more beautiful one. Most consumers have yet to understand that two diamonds with the exact same weight, color and clarity can be purchased up to 40% cheaper if the cut is poor. This trade secret allows some jewelers to buy very poor makes and sell them in turn at prices reserved only for beautifully cut stones.

DIAMOND DESCRIPTION

A diamond is divided into three sections:

Crown - the upper section of the diamond

Pavilion - the lower section of the diamond

Girdle - the rim separating the crown (top)

from the pavilion (bottom)

A round brilliant diamond has between 57 and 58 facets (depending on whether the culet was polished) divided into 7 different parts. On the crown, there is a large octagonal table surrounded by 8 triangular star facets; 8 kite bezel facets and 16 triangular upper girdle facets, arranged in pairs that circle the crown's perimeter. A culet on the pavilion connects 8 elongated, kite-shaped pavilion mains to the girdles' edge. Separating the pavilion mains are 16 elongated, triangular lower girdle facets arranged in pairs.

Every diamond lab has small variations of what a beautifully cut diamond's proportions should be. The leading gemology labs agree on the following proportions:

The relationship between the sizes and angles of these parts and facets is what creates the valuable display of brilliance, sparkle and fire. When analyzing a diamond's proportions be on the lookout for the following:

Table size percent - The percentage of the table relative to girdle diameter

Crown angle - The angle between the bezel facets and the girdle

Girdle thickness - Assessing girdle thickness is done by eye; it ranges from extremely thin to extremely thick.

Depth % - The height of the diamond expressed as a percentage of girdle diameter

Culet size - Assessing culet size is done by eye; it ranges from pointed to extremely large.

Symmetry - The equality between corresponding parts of the diamond graded from poor to excellent

Polish - The quality of the facets' polish graded from poor to excellent

Any deviation on even one of these parameters can totally change the appearance of the diamond. Let's analyze a diamond with the following parameters: 58% table, 34.5 degree crown angle, slightly thick girdle, 64.5% pavilion depth %, no culet, excellent symmetry, very good polish. To the inexperienced eye this is a beautiful diamond. Except for the diamond's depth all the proportions are ideal. A closer look reveals that the stone is too deep causing light to leak out and thus resulting in poor brilliance. Except for the diamond's depth all the proportions are ideal. A closer look reveals that the stone is too deep causing light to leak out and thus resulting in poor brilliance.