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Diamond Cut

Learn about cut, which determines a diamond’s beauty, sparkle, fire and brilliance.

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What Is the Cut of a Diamond?

The cut of a diamond refers not to its shape, but to the balance of proportion, symmetry and polish achieved by the diamond cutter. The extent of how well the diamond is cut is directly correlated to the diamond’s overall beauty. The better a diamond has been cut, the greater the diamond’s ability to reflect and refract light. Modern diamond cutters understand the way that light moves through diamonds and have established a set of specific proportions and angles to best optimize the diamond’s internal brilliance and show it in its best light.

Types of Reflection

What is Brilliance?

Brilliance, or brightness, refers to the white light that is reflected back to the eye from the diamond. Light enters through the top of the diamond (the table), is broken down into a rainbow of spectral colors, and is reflected back and forth in the interior of the gem by bouncing off the mirror-like facets. Light exits through the table, recombining as white light.

What is Dispersion? (Fire)

Dispersion is the rainbow of colors that is reflected back to the eye from the diamond. Light enters through the top of the diamond, is broken down into a rainbow of spectral colors, and is reflected back and forth in the interior of the gem by bouncing off the mirror-like facets. When it leaves through the crown, it stays separated and reaches the eye in flashes of color.

What is Scintillation?

Scintillation is the play of light you see with movement of the diamond, demonstrated by sparkling on the diamond's surface. A diamond is evaluated on its ability to reflect and refract light in all directions.

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What are Diamond Characteristics?

Several proportion factors of a diamond have an immediate impact on the diamond’s ability to reflect light. The table size and depth of a diamond relative to the diameter greatly impacts the light return from a diamond.

Table

The flat surface at the top of the diamond

How is Diamond Cut Graded?

GIA, considered to be one of the most respected laboratories for grading natural diamonds, uses the following language on their certificates to grade cut for round diamonds: Excellent, Very Good, Good, Fair, Poor. A GIA Excellent cut will be listed as either Ideal or Super Ideal on the Brilliant Earth site. Brilliant Earth uses specific diamond characteristics, such as cut grade, polish, and symmetry to distinguish between Ideal and Super Ideal. If a cut grade is not available from a grading laboratory, such as for fancy shaped diamonds, Brilliant Earth combines the characteristics above along with depth, table, secondary measurements, and subjective factors to assess the cut grade of the diamond.

How Important is Diamond Cut?

Several proportion factors have the most immediate impact on a diamond's ability to reflect light correctly. The table size and depth of a diamond relative to the diameter greatly impacts the light return from a diamond.

Diamond Cut Chart

super Ideal Cut to the most exacting standards. These diamonds have the most desirable dimensions and are proportioned to return the maximum possible light. Round diamonds will show a "hearts and arrows" facet pattern.
Ideal Exquisite quality cut to create the optimal combination of brilliance and fire. Reflects nearly all light that enters the diamond. Top 3% of diamond quality based on cut.
Very good Superior quality cut that reflects nearly as much light as the ideal cut while at a substantially lower cost.
good Premium quality cut to optimize the size without sacrificing quality or beauty. Reflects most light that enters.
fair Adequate quality cut that reflects some light while maximizing weight. While not as brilliant as a good cut, still a quality diamond.
Poor Not carried by Brilliant Earth.
Rose gold three-stone radiant cut diamond engagement ring.

How does Cut Impact Types of Reflection?

A well-cut diamond 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 fire (dispersion). A poorly-cut diamond, with facets cut only a few degrees out of alignment, can result in light exiting through the bottom of the diamond, known as light leakage, instead of from the top where it is visible. This creates a diamond with dulled brilliance from poor light performance within the gem, making the center of the gem look dark.

Diamond Cut FAQ
Cut is considered to be the most important of all of the diamond characteristics, as a well-cut diamond will often appear larger than a poorly-cut diamond of the same carat weight, and have the appearance of enhanced color and clarity.
Super Ideal diamonds are cut to the most exact standards and achieve the most sparkle because they are proportioned to return the maximum possible light.
Looking at cut alone, Super Ideal diamonds are likely the most expensive, but the price of a diamond is based on other diamond characteristics as well, such as color, clarity, and carat.
Diamond shape refers to a diamond’s physical form and is often one of the first attributes that couples consider when shopping for a diamond. Diamond shapes include round, oval, cushion, princess, pear, emerald, marquise, asscher, radiant, and heart shaped diamonds. Diamond cut does not refer to the physical shape of the diamond, but the balance of proportion, symmetry, and polish achieved by the diamond cutter.