All about form, cut grade and the arrangement of facets.
The cut grade of a diamond directly affects the irresistible sparkle.
When it comes to the shape of a diamond, you need to differentiate between round, oval, pear, and so on. The cut grade, however, measures how well the facets are made and arranged. The GIA only assesses the cut grade of a round stone; for all other shapes, GIA merely offers grades on Symmetry and Polish, because there is no perfect oval, for example. A round stone, however, needs to be perfectly round.
Diamond shapes – Popular cuts
The round brilliant cut is regarded as the most popular and classic shape. All other shapes are referred to as “fancy cuts”. There’s a whole set of popular diamond shapes. Each one of them corresponds to a typical form and arrangement of facets. Some of the most popular shapes are:
The cut grade scale
The GIA cut grade scale ranges from Excellent to Poor. Each cut grade represents a whole range of proportions and face-up appearances.
Excellent: The diamond has an even pattern of bright and dark areas. It receives top scores in all categories.
Very good: The relation of dark and bright areas is well balanced.
Good: The diamond’s scintillation limits its grade. A relatively shallow pavilion angle produces dark pavilion mains. (Grade limitation concerning scintillation)
Fair: A relatively shallow pavilion angle is combined with a shallow crown angle. Consequently, the face-up appearance lacks contrast and a general darkness can be observed. (Grade limitation concerning scintillation)
Poor: A thick girdle greatly increases the diamond’s total depth. Therefore, its diameter is much smaller than normal for its carat weight. Hence, the diamond’s grade is limited by its weight ratio.
What’s the minimum cut grade you should go for?
As mentioned before, the cut grade is largely responsible for a diamond’s sparkle and therefore an important contribution to the overall quality of a diamond. When selecting a stone, it is important to find the right trade-off between the 4Cs for oneself. Read here how to define this trade-off and what minimum cut grade you should go for.