Understanding Diamond Cuts
a guide to different diamond cuts
WHAT IS A DIAMOND'S CUT?
A diamond's cut quality refers to the proportioning, symmetry, and polish of a diamond rather than the shape of the stone. The quality of the cut of a diamond is directly related to the overall beauty of the stone. The cut grade considers the depth of the stone and how well the diamond's facets (flat surfaces on the stone) interact with the light. If a diamond is ideally cut, the light will reflect and refract in a way that maximizes brilliance for that shape.
Expert workmanship and stone cutting skills are required to cut a diamond to reflect and return as much light and brightness as possible. The better the diamond is cut, the better the ability to reflect light.
A well-cut diamond design is proportioned so that most of the light entering the gem exits back through the top of the stone, perfectly balancing the white light (brilliance) with intense flashes of colorful fire (dispersion). When a diamond is out of proportion, even by a little, it does not reflect the light back up to the top of the diamond and leaks out through the bottom the stone.
The absolute beauty of a diamond lies in its brilliance. Diamonds must reflect the white light that enters the diamond back toward you. The more facets a diamond has, the more opportunities light has to display the flashes of light back to you.
HOW ARE DIAMONDS GRADED?
Gemologists analyze the cut grade by calculating the proportions of the facets that affect the appearance of the diamond. When grading the cut, they consider brightness (internal and external white light reflected), fire (scattering for white light into colors of the rainbow) and scintillation (amount of sparkle).
The cut grade also covers the craftsmanship of the diamond. This is shown in the symmetry, quality of polish, weight relative to diameter and girdle thickness. A diamond with an excellent cut reflects white and colored light, while a poor cut diamond can seem dark and dull.
The GIA scale grades round diamonds from Excellent to Poor. The round diamond is the only shape considered ideal and the only one that receives a cut grade from labs. All other shapes are considered “Fancy Cuts”, and the cut scale does not apply to them in the same way. But they do receive grades for polish and symmetry. You can look at these as well as the measurements to determine if the stone is cut well.
Diamond cut chart
Excellent: The best type of diamond cut. Reflects most of the light that enters the diamond and is in the top 3% of diamond cut quality.
Very Good: Reflects about the same amount of light that enters the diamond and in the top 15% of diamond cut quality. A very popular diamond cut especially for engagement rings.
Good: Reflects a good amount of light that enters the diamond, but not as much as Very Good, and is in the top 25% of diamond cut quality. They will not be as bright as the ratio disrupts the light reflection.
