When choosing a diamond, one of the characteristics you should pay the most attention to is cut. And for good reason: Diamond cut greatly affects how bright and brilliant a stone looks. If you want to learn how diamond cuts are classified, graded, and compared, read on.
How Are Diamond Cuts Classified?
The main defining feature of a diamond cut is its shape. Cuts can be round, oval, triangular, rectangular, etc.
The classic diamond cut is the round brilliant cut, and all other cuts that are not round are often referred to as “fancy cuts.”
Every diamond cut can be judged on a variety of parameters such as the depth of the stone, its width, the area of its top, as well as a number of other proportions.
The most comprehensive system for cut assessment that has been created is that used to evaluate the round cut, which is by far the most popular one.
How Is the Round Diamond Cut Graded?
The round diamond cut is evaluated according to how close its proportions are to those of the so-called “ideal cut,” i.e., a cut with measurements that allow a diamond to reflect light in a way that maximizes the stone’s brilliance.
There are different systems for cut grading, and one of the most popular scales is that of the GIA (Gemological Institute of America), which assigns the following grades to round cuts: Excellent, Very Good, Good, Fair, and Poor.
An alternative system is that of the AGS (American Gem Society), which uses similar grades: Ideal, Excellent, Very Good, Good, Fair, and Poor.
Comparing Round Diamond Cuts
There are a lot of parameters that are factored into the cut grade of a particular round stone, but the most important proportions that define the quality of round cuts are table diameter, crown height, and pavilion depth.
Table diameter is a measure that refers to the diameter of the stone’s top surface expressed as a percentage of the diamond’s girdle (edge). For most top-quality diamonds, this proportion is in the 53%-57% range.
Crown height refers to the distance from the stone’s top to its girdle. According to the most popular ideal-cut standards in use today, it is recommended that this measure should be between 14% and 16%.
Pavilion depth is the height of the lower part of the diamond – from its girdle to its bottom. Well-cut stones have a pavilion that is about 43% of the girdle.
If the diamonds you are looking at are certified by a grading lab (such as the GIA), they should have their proportions listed on their certificates.
When examining a graded stone, the quickest way to compare its cut to others is to simply look at its cut grade, which represents an integrated evaluation of all cut proportions that are deemed important.
When comparing diamond cuts of different levels of quality, the most visible distinction that separates the good from the poor cuts is the way a diamond interacts with light.
Well-cut stones have more brilliance and sparkle, whereas poorly cut ones look darker and duller in comparison.
Round Cut vs. Other Diamond Cuts
Although there is a well-developed evaluation system for the round cut, this is not the case with most other cuts – for them, there are hardly any universal rules and measurements that constitute an “ideal” cut.
It is worth noting that the round brilliant cut was created to maximize brilliance, which can mask some imperfections in the stone to an extent.
In general, other cuts have less sparkle than round diamonds. As a result, round stones exhibit less color and their inclusions are less visible compared with stones of other cuts with the same color and clarity grades.
When comparing nonround diamonds with each other, it is advisable to pay attention to how they compare on depth.
If a stone is too shallow, it may lack brilliance compared with a deeper diamond, and that is something you should assess on a case-by-case basis.
Cuts that are too deep, on the other hand, will give you less surface area on the top of the stone, and as a result, the diamond will look smaller when mounted in a setting (compared with a shallower stone of the same carat weight).