Cut quality of diamond has a great impact on its brilliance and sparkle.
So, it is important to understand the significance of diamond's cut
If a diamond is well cut, incident light enters through its table and crown, travels towards the pavilion where it reflects and falls on opposite side of pavilion, before reflecting back out of the diamond through the table towards the observer’s eye. This phenomenon of total internal reflection of light makes diamond mesmerizing and unique among all gemstones.
If the facets of diamond are unsymmetrical or if cut of diamond is not according to proportions or if diamond is not polished properly, then it affects the quality of light reflection which then impacts the brilliance, dispersion and brightness of diamond.
How cut of diamond affects the path of light passing through diamond?
In Shallow cut and Deep cut diamonds, the incident light enters through the table, reaches the pavilion and then refracts out from the sides or bottom of the diamond instead of reflecting back to observer’s eye through the table.
Due to this, shallow and deep cut diamonds possess less brilliance as compared to Ideal cut diamond in which the maximum amount of incident light is reflected back to the observer’s eyes through the pavilion. Check the below image.
Variations in cuts result in difference in sparkle and brilliance of diamond. However, only an expert grader can make out the difference between various cuts.
Grading of Cut Quality of Diamond
Diamond Cuts are classified into various grades. These grades are as follows with decreasing quality of cut: