Cut is regarded as the most important factor out of all the 4Cs as the allure and beauty of a diamond depends very much on the cut quality.
Cut refers to the angles and proportions of a diamond. These elements affects how well light interacts with the diamond.
A well cut diamond requires precise artistry and workmanship. If the angles and proportions of the diamond are optimised, it will prevent light leakage from the bottom and the sides of the diamond.
The higher the Cut grade of a diamond, the more it will exhibit a brilliant shine and magnificent sparkle as more light returns through the top of the diamond to the eyes.
GIA grades the Cut quality based on the assessment of seven components. The first three components which assesses the diamond’s overall face-up appearance are brightness, fire, and scintillation.
Brightness is the total light that is reflected from a diamond. Fire is the dispersion of light into the colours of the spectrum. Scintillation is the flashes of light or sparkle when a diamond is moved back and forth.
The other four components are weight ratio, durability, polish, and symmetry which assesses a diamond’s design and craftmanship.
Each component is assessed individually and based on the relative importance of each component, a cut grade is given on a relative scale from Excellent to Poor.
Only standard brilliant round diamonds come with a Cut grade as it is established by comparing the measurements of the diamond’s facets against a database of more than 38.5 million proportions sets of known grades.
Establishing quality parameters for fancy shaped diamonds are much more complex than for round diamonds and measuring technology currently are not sufficient to capture the features considered important for fancy shape diamonds.