Diamond Cut
The Cut is the most objective and scientific measurement of a diamond’s proportions, arrangement and alignment of the facets, and quality of the polish. In a perfect-cut stone, the light entering the diamond reflects and refracts creating the fire, brilliance, and scintillation (“sparkle”) in the stone.
The Cut is a result of the artistry and craftsmanship of the diamond cutter, to maximise the return of light. Diamonds vary in cut, and it's the first most visible factor to the naked eye.
Of the 4 Cs, the "Cut" is the most crucial component to a particular stone’s overall beauty. The Cut should not be confused with the “shape” of a diamond. The Cut is only measured for Round Brilliant diamonds. All other shapes do not receive a “Cut” grade, but rather a polish and symmetry grade. The “Cut” is therefore more subjective for these shapes, and the beauty of the stone is more subject to the overall “look” that you may be trying to achieve.
GIA grades diamonds cut for Round Brilliant diamonds according to the following criteria-