Where Do Star Facets Appear In A Diamond?


A beautiful diamond is determined by how the diamond looks. And the visual beauty that is showcased by it to the observer. According to the gemological labs and societies all over the world. The 4 C’s has the most vital role in enhancing the value and beauty of a diamond. And, among all the four C’s, the Cut plays a major role in defining the best characteristics that a diamond has to offer. Before going into the questions about “Star Facets” let us look in more detail about the factors and characteristics of the anatomy of a diamond.

The Diamond Anatomy


Just as the human anatomy showcases the features about the human body, by extensive researches and studies. Scientists have created a specific set of terms that are used to describe the features and parts. That a complete and polished diamond has to offer. Each of these parts plays a vital role in contributing to the overall enhancement of the diamond’s visual appearance and appeal.

For detailed clarification, we will consider the diamond to be a round brilliant-cut one.

A round brilliant cut diamond comprises of 58 facets. Among all the facets, the largest facet on the diamond is known as the table facet. And it reflects exterior light either within the diamond interior or back to the viewers or the observer’s eyes.

Then there are crown facets, which consist of 8 stars, 8 bezels, and 16 upper halves. And their job is to gather and disperse the source light to create beautiful patterns of light and dark. Enhancing the scintillation properties of the diamond. There are pavilion facets, which consist of 8 mains, 16 lower halves, and a culet (optional), and they aid in reflecting light to the observer’s eye through the diamond’s crown. All of these facets together, work, and aid in creating the unique beauty and appearance of the diamond. And makes it one of the most mesmerizing gemstones of all.

Let’s now, discuss the technicalities in a bit detail-

Total depth percentage


This is calculate by creating a percentile of the value that is obtain by dividing the depth of the diamond with the average girdle diameter.

The formula to calculate it is as follows-

Total depth percentage = (depth / average girdle diameter) x 100

Average girdle diameter


The distance between one girdle edge to the opposite girdle edge is the diameter of a round diamond. As all well-cut round diamonds are not perfect. The minimum and the maximum measurements are taken and then their average is calculated out.

The mathematical formula for calculating the average girdle diameter is as follows-

Average girdle diameter= (maximum diameter + minimum diameter) / 2

Star length percentage


The length of the star facet expressed as a percentage of girdles to table distance is refer to as Star length percentage. They are typically describe to the nearest five percent of the average of the eight-star length percentages.

Table percentage


The percentage of the value that is calculate by dividing the average table size with average girdle diameter is refer to as the Table percentage. The measurements of the table sizes are generally the distances from one bezel point to others.

The mathematical formal to calculate the table percentage is as mentioned below-

Table percentage= (average table size / average girdle diameter) x 100

When paired with combinations of pavilion and crown angles. The table size has a great impact on the face-up appearance of a diamond.

Crown height percentage


This is calculate by dividing the average crown height with the average girdle diameter and changing it to a percentile form. It is also refer to as the measurement from the table to the intersection of the bezel facet and the girdle.

The following formula is used to calculate it-

Crown height percentage = (average crown height / average girdle diameter) x 100

Crown angle


The angle between the bezel facet plane and the table plane is refer to as the crown angle. It has a significant effect on a diamond’s visual appearance. The general rule for obtaining a bright and attractive diamond is for its crown angle to be anything from 32 to 36 degrees. It is calculate by deducing the average of the eight crown angle measurements to its nearest half- degree.

Pavilion depth percentage


The depth of a pavilion is the measurement of the distance from the culet to the intersection of the main pavilion facet and girdle.

The following formula is used to calculate the pavilion depth percentage

Pavilion depth percentage= (average pavilion depth / average girdle diameter) x 100

Pavilion angle


The measured angle between the pavilion main facet and the table plane is refer to as the Pavilion angle. It has an important impact on the appearance of the diamond. If the angles are steep, they can produce dark areas under the diamond’s table.

Girdle thickness description


The range between the thinnest and the thickest areas or “valley” positions is refer to as the girdle thickness. It is generally scale from the highest value of extremely thick to that of the lowest value which is extremely thin.

Girdle Thickness percentage


It is the percentile value of the thickness of the diamond’s girdle and is typically measure at the main “hill” positions or bezel positions.

Lower half-length percentage


 It is the length of a pair of lower half facets expresses as a percentile of the girdle to cult distance. 

Shorter lower-half facets diminish the visual appearance of a diamond by negatively impacting its pattern.

What are Star Facets and where do they appear?


The facets which border on top of the table facet of the diamond are refer to as Star Facets. They are label such simply because, if visualize together, they form the shape of a star.

The star facets play a vital role in pathing the light ways to various directions to and from the diamonds. Resulting in enhancement of its brilliance. If all the star facets are visualize together, they form an octagon shape and are among those of the facets of a diamond. That are directly viewable to anyone who looks at it. It is require that these facets are to be perfectly symmetrical, cause if it is not; then it will affect the total symmetrical look of the diamond and result in making the diamond unattractive.

Star facets are also one of the ending jobs that the cutter needs to focus on. Simply said, it plays a role in “connecting all the dots” or facets of the diamond and signifies the overall eccentricity, scintillation, and brilliance of the diamond.