DGI 4C’s - Cut

Unlike Color and Clarity, the cut parameter is completely under human control, and isn’t determined by nature. However, just like carat, the cutters base their choice of cut and size by the inclusions and defects inside the rough stone, to create the biggest beautiful as possible polished diamond.

The cut parameter is a combination of two parameters: Shape which is also called “CUT”, and Cut which stands for the proprtions and quality of the diamonds polish and cut.

Here we will learn about both of these criteria, the many shapes in which diamonds can be formed into, and the grading scale for the diamonds “cut grade”, polish and symmetery etc..

Shape (also called ‘CUT’)

The first and more important parameter is the shape of the diamond, it is also the most simple of all the parameters in the 4C’s. There are many shapes in which a diamond can be cut. Every shape has a different price and different qualities.

The shape of the diamond is in fact created by many tiny flat surfaces combined in certain angles formed by the diamond cutter in order to create the required shape. these flat surfaces are called “facets”.

Here are some basic shapes for polished diamond.

Round Brilliant.
Cushion Shape.
Pear Shape.
Heart Shape.
Princess Cut.

The round diamond is the most popular shape from all shapes, and has most rules regarding its quality. The other shapes are known as “Fancy Shapes”, they are just as beautiful but a bit less popular.


Cut (Proportions, Polish, Symmetry)

The second parameter is the quality of the diamonds polish, how symmetric it is, and how well does it break the light. the better the diamonds cut, symmetry and polish are – the better it will break the light, and the better it will break the light – the more it will “Sparkle”.

Heres how the light breaks inside the diamond

The polish and symmetry go on a scale between “Poor” and “Excellent”:

Worst: Best:
Poor Fair Good Very Good Excellent

The cut grade, polish and symmetry parameters are based on the proportions of different parts of the diamond: the diameter (width and length), the height (total depth), table, pavilion, crown and girdle, as seen here:

– Facet: diamonds we see may be round, square or any other shape, but what is in common to all of the diamonds shapes, is the fact that the shape is formed by different angles and sizes of facets. Each facet is basically a flat surface of the diamond formed by the cutters and polishers of the diamond. The combination of size and angle of these facets create the external shape of the diamond. This is NOT a criteria in gemological reports.

- Diameter:  the external diameter of the diamonds (measured of course in the diamonds widest part – the girdle – the belt that goes around the diamond when you look at it facing up, as mounted in jewelry), usually this diameter is described with two numbers that stand for the shortest and longest diameter of the diamond in mm. These numbers will be the first two numbers in the “measurements” critiria in our reports.
For example:
Measurements: 5.24 mm. – 5.20 mm. x 3.12 mm.
Here 5.24 mm. – 5.20 mm. are the diamonds diameter, 5.24 mm. is the widest part of the diamond, and 5.20 mm. is where it is most narrow. Of course this works in both round brilliant cut diamonds as well as fancy shaped diamond.
The average between these two numbers is also the scale by which we measure all the other parts of the stone. In other words, the average diameter is the 100% for all the characteristics that are measured in percentages (like Total Depth, Crown Height, etc.).

- Height (Total Depth): The external height of the diamond when we look at it from the side (not facing up as we do when measuring its diameter). this characteristic is described in both mm., like the diameter, and percentages.
The height of the diamond in mm. will appear in the measurements criteria of our reports, as the last number, after the two that stands for the diameter.
For example:
Measurements: 5.24 mm. – 5.20 mm. x 3.12 mm.
Here 3.12 mm. stands for the diamond height in mm.
The height of the diamond in percentages will appear under “Total Depth”. Here, of course, the percents are on a scale in which a 100% is the diamond average diameter.

- Table:  Table is referring to the size of the flat part at the top of the diamond. The part we look through when we look at the diamond as it faces up (like on a jewel). This criteria is measured in percentages, the percentages are in correlation to the diamonds average external diameter.

- Pavilion: The pavilion is referring to the facets beneath the girdle (from the girdle to the culet), basically the back of the diamond. These are usually the biggest facets in the diamond except for the table. This criteria is measured in percentages.

- Crown: The diamonds upper facets, above the girdle (from the girdle to the table). The height of the crown is very important to the diamonds proportions, and it is measured in percentages.

- Girdle: The widest part of the diamond or belt that surrounds the diamond, round belt if it is a round brilliant diamond, square for princess cut etc. this criteria in gemological reports is referring to the height of the girdle, if a girdle is extremely thick this will affect on the diamonds proportions and of course on the way the light breaks inside the diamond. This criteria is on a basic scale of thin to extremely thick.

- Culet: The culet is referring to any flaws in the pointy edge at the bottom of the diamond. this criteria tells us if the diamonds pointy edge is broken, trimmed or just not complete. Therefore None is the best grade for this criteria.


In some cases the proportions of the diamond create unique combinations, such as “8 Hearts & 8 Arrows”, “Tolkowsky Ideal Cut” and others, which indicate precision cut and symmetry, to form superb and unique light reflections inside the diamond.

“8 Heart & 8 Arrows” is tested under a special instrument wich uses a red light from certain angles to form unique reflections inside the stone, if it is indeed a real “8 Hearts & 8 Arrows” stone. these reflections actually look like 8 hearts and 8 arrows facing from the center of the stone to the outer surface, and thats how they got their name. as shown here:



the diameter of the diamond can also indicate its weight (usually used to tell the weight of stones that are mounted in jewels), however this is only an indication of the common size measurements per weight, depending on the shape and cut of the diamond. for further information on diamond weight see Carat



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