Diamond Cut

At A Glance

• Cut is likely the single most important characteristic in the appearance of a diamond.
• The cut is what unleashes a diamond's fire, sparkle, and brilliance.
• It has the most comprehensive influence on the beauty of a diamond.

What is a Diamond Cut?

The industry uses the word "cut" in reference to a diamond in two ways. Most people tend to think of diamond cut as what actually is referring to the shape, such as an emerald cut diamond. Round is the most commonly used shape in diamond jewelry, while the assortment of other shapes are considered fancy shapes, like the marquise, oval, and pear. (You will learn about shapes more intimately in the Shapes section of this Diamond Education Guide.) The second use of "diamond cut" is used to depict the reflective qualities of a diamond. The reflective quality a diamond possesses is a direct result of how well it was cut. It is the second use of the term "cut" that applies in receiving a grade and notation on diamond certificates.

No other characteristic has a greater influence on the appearance of a diamond, from lustrous to dull. The cut of a diamond is perhaps the most important characteristic of the four C's, as it is the factor that unleashes a diamond's fire, sparkle, and brilliance. A diamond's cut grade is an objective measure and insight into a diamond's light performance, commonly referred to as sparkle. With a good cut, a diamond gains brilliance, which is the brightness that radiates from the very heart of the diamond. It is the angles a diamond was cut into and its finish that facilitate its ability to harness light, creating the brilliance we covet so much in diamonds. Thus, understanding how the cut affects the properties of and value of a diamond is important when choosing a diamond.

Cutting a diamond is all about harnessing light to flow through it with precision and control the lights journey to burst straight through the crown of the diamond. The images above depict different cuts, with a variety of ways light can enter and exit a diamond. When a diamond is well-cut, light will enter through the table of the diamond and makes its journey to the pavilion. Before it ever reaches the observer's eye, the light will have reflected from one side to the other before finally reflecting back once again out of the table of the diamond. This precise and elegant control of light is what we call brilliance, the mesmerizing effect that flashes with fiery splendor. It is why we adore diamonds so much and value them as they should be.

However, with a poorly cut diamond you will not see the aforementioned brilliance. The light is not properly harnessed and will enter through the table, but instead of reflecting back to the observer's eye, it will only leak out from the sides or bottom. The lesser amount of light that is reflected back to reach the observer's eye ultimately means less brilliance. This is the reason that a diamond's cut grade is so pivotal and should be your first priority.

How is a Diamond Cut Graded?

gia cut scale

Analyzing and quantifying the cut of a diamond is extremely difficult, but it is broken down to three attributes:

• Brilliance: The total white light, both internal and external, reflected from a diamond
• Fire: The dispersion of white light into a prism of all the colors of the rainbow
• Scintillation: The pattern of light and dark areas caused by reflections within the diamond, as well as the flashes of light, or the amount of sparkle, a diamond produces

Traditionally, a round brilliant diamond will possess 58 facets; each precisely cut and defined to harness light. They can be as tiny as two millimeters in diameter. It is the precision in which a diamond is cut that creates the brilliance and without it, a diamond would not be nearly as exquisite. There is a set formulae calculated to maximize brilliance that most gemologists agree, if followed, creates the best cut diamonds. The formula primarily rests on a keen awareness of the diamond's proportions, with two factors playing the greatest roles:

• How the depth of the diamond compares to the diameter
• How the diameter of the table of the diamond compares to the entire diameter of the diamond

The value of the cut relies on a diamond's proportions, symmetry, and polish. Proportions can greatly change the appearance of the diamond, which refers to the relationships between table size, crown angle, and pavilion depth. There is a range of many proportion combinations that are feasible, each affecting the diamond's interaction with light. Pavilion depth is a pivotal characteristic that can impact the diamond both positively or negatively. When the depth is either too deep or too shallow, it will permit light to escape through the bottom of the diamond or out through the sides. Meanwhile, a well-cut diamond will have the optimal pavilion depth that will direct the most light possible through the crown.

For the casual observer, discerning the difference in the proportions between an Ideal Cut and a Poor Cut can be difficult. If you decide to purchase a diamond that doesn't possess a GIA or an AGS certificate, you should train your eyes to recognize better cuts and their overall brilliance by dedicating time to observing certified diamonds that you know the cut grade.

Several grading methods have been developed and, like the rest of the 4C's, the GIA has created the standard for grading the cut of a diamond. The GIA Diamond Cut Scale is the product of years of intensive research and testing, ultimately assigning diamonds an overall cut grade ranging from Excellent to Poor. One of the first aspects that are analyzed is how successfully a diamond interacts with light to create the desired visual effects by calculating the proportions of the facets that influence the diamond's face-up appearance. The cut grade also takes into account the craftsmanship and design of the diamond. This includes its carat weights relative to its diameter, the symmetry of its facet arrangement, the quality of polish on those facets, and the diamonds girdle thickness.

Which cut grade is right for me?

Considering the cut grade of a diamond is the single most influential factor in how the diamond will appear and whether or not it will exhibit the visual brilliance that only a diamond can, you should purchase the highest cut grade you can afford. If you can't afford Ideal or Excellent, then a cut grade of good or very good embodies a superb combination of beauty and value. To make the best selection, you first should understand the various grades and make your decision based on your preference. Please note that the descriptions below are general guidelines and for further analysis, you should view stones of various cut grades to fully understand the differences.

Diamond Anatomy