The third C is misleading, as there is more to the Cut of a diamond than meets the eye. While choosing between an emerald cut or a princess cut is certainly a major part of diamond selection, this Cut refers to the diamond’s light performance. If you want to see your diamond really sparkle, this is where the cut makes all the difference.
It is also this C in the diamond’s evaluation that is the most complex and technically difficult to analyze. It requires precision and workmanship to fashion a stone so all its unique elements work together to return the desired light only a diamond can.
Determined by the GIA, the Diamond Cut Scale ranges from Excellent to Poor, representing how well the diamond’s surfaces interact with light. The GIA uses the standard round diamond to calculate the proportions of each of the diamond’s surfaces that contribute to its face-up appearance.
Some of the different ways to measure a diamond’s cut is through brightness, through its fire or the white light scattered into the colours of a rainbow, or by its scintillation, the technical term for the diamond’s sparkle (patterns of light and dark reflections).
Along with the measurement of light through this evaluation stage, the cut of a diamond is also ranked on design and craftsmanship, including the different arrangements and polishes of the many surfaces within the diamond.