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Diamond Cuts

Learn about diamond cuts, which determine a diamond’s beauty, sparkle, fire and brilliance.

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Why Is A Diamond’s Cut Important?

Diamond cut is one of the most crucial elements to consider when selecting a diamond. The cut refers not to the shape of a diamond, but 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 how light moves through diamonds and have established a set of specific proportions and angles to best optimize the diamond's inner brilliance.

Before they are worked, natural diamonds resemble two square pyramids arranged in an eight-sided octahedral. A point-cut diamond is still in its natural shape and polished. While still quite beautiful, this cut does little to maximize the effects of light moving through the stone.

Three proportion factors directly impact a diamond's ability to reflect light correctly: table, width, and depth. The table size and depth of a diamond relative to the diameter dramatically impact the light return from a diamond. At the same time, the proper width ensures that light hits the critical refraction angle.

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).

On the other hand, a diamond cut even a few degrees out of proportion can tunnel light out of the bottom of the diamond rather than redirect it back up towards the table, a phenomenon known as light leakage. This leak creates a diamond with poor light performance, dulled brilliance, and a dark center that cloaks its natural sparkle.

Types of Light Reflection

What is Brilliance?

The absolute beauty of a diamond lies in its brilliance. Diamond cutters know that for a diamond to truly shine, it must reflect and radiate white light from the mirror-like facets back toward the viewer.

There are two types of facets within a diamond: physical and virtual. Physical facets are those that are cut into the stone. As they bounce and reflect light towards the viewer, it appears that there are hundreds of flashing lights within the gem, despite there only being a limited number of cuts in the stone. These flashes are the virtual facets.

Each time light enters a diamond, the physical facets send it off in different directions, depending on the angle and tilt. As the angle of the light changes, so does the set of facets interacting with one another to send the light back through the table. The prismatic lights recombine as brilliant, white light as it exits back through the table.

The more physical facets a diamond has, the more opportunities for light to create a dazzling display of flashing lights. Masterfully cut diamonds demonstrate superb brilliance because they bounce light off multiple surfaces, creating a multiplier effect that seems to reflect far more than the sum of its parts.

What is Fire

Light is made of an entire spectrum of colors that combine into what we perceive as white. As the waves of light travel through the air, they move incredibly fast until they collide with a surface that slows them down.

Diamonds are excellent at slowing down light, scattering it into its parts, and displaying a shimmering spectrum of color. As white light enters through the stone's table, it bends and refracts off of the mirror-like facets in countless directions, regaining speed.

The name of this effect is dispersion, or is commonly referred to as fire. It creates a dazzling display of color that adds undeniably beautiful vitality to a stone. A high-quality diamond should show flashes of color deep within the stone, glinting sparks of red, orange, yellow, green, blue, and purple as light ricochets over the cut facets. This effect gives diamonds effervescence and liveliness.

Diamonds must be precisely cut for light to hit the critical angle at which the full dispersion potential is realized. Imprecise cuts do not refract and scatter light as efficiently, allowing the white light to escape instead of breaking into its individual colors amongst the facets.

What is Scintillation?

Often referred to as a diamond's "sparkle," scintillation is a dynamic cut characteristic created by the interplay of flash scintillation (white light) and fire scintillation (multi-colored light).

As you move a diamond in the light, the facets split the white light into a spectrum of colors, creating sparks of light that appear to dance along the surface of the diamond. This is contrasted sharply against the darker, colored flashes that refract through the inner facets.

The symmetry and balance between lighter and darker areas create the overall sparkle. Much of the effect will be lost as light escapes through the pavilion and culet without this pronounced contrast.

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What Diamond Characteristics
Impact Cut?

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 dramatically impact the light return from a diamond.

Table

The flat surface at the top of the diamond

Different Types of Diamond Cuts

Super Ideal Diamond Cut

The Super Ideal Diamond Cut includes only gems with the most desirable dimensions and appropriate proportions that ignite the brilliance, dispersion, and scintillation within. This grade demonstrates superior craftsmanship and excellence in its class.

Ideal Diamond Cut

To the untrained eye, a diamond with an Ideal grade is just as brilliant and fiery as a Super Ideal Diamond. Ideal diamonds may have a lower clarity or color grade, but the lower grade is more than likely associated with a small amount of light leakage. This is a popular choice for engagement rings because it is visually identical to Super Ideal diamonds.

Very Good Diamond Cut

A Very Good cut diamond will still present with incredible light return and exceptional brilliance, as most of the light entering the table will refract the way it is expected. A Very Good cut diamond often has proportions that offset the appropriate weight-to-size ratio or undermine the facet balance. This is a popular diamond cut, as they reflect nearly the same amount of light for a much lower price point.

Good Diamond Cut

Good cut diamonds are ideal for a larger carat, as they leave weight while still reflecting plenty of light. The proportions within a diamond of this grade will be only slightly imperfect, which allows them to reflect the majority of light. Good diamonds will not be as bright, as the ratios will leave more dark spaces in the stone, causing it to look duller than a comparable gem of a higher grade.

Fair Diamond Cut

A diamond graded as Fair will have a marked reduction in fire and scintillation, as the balance between light and dark areas is not symmetrical. The brilliance will also be affected, with light leaking through the pavilion. Fair diamonds are more likely to have a smaller carat, best serving as side stones. The smaller size makes it challenging to see a loss of sparkle or brilliance. This gives rings a higher total carat count, an adequate light return, and a reduced price point.

Poor Diamond Cut

A Poor diamond cut allows most light to spill out from the pavilion and culet. When viewed face-up, there are prominent areas of darkness where the facets cannot refract or reflect the light towards the table. Brilliant Earth does not carry Poor cut diamonds.

How Are Diamond Cuts Graded?

After 15 years of studying how light interacts with a round brilliant cut diamond, the Gemology Institute of America, or GIA, has explained seven components determining a diamond’s cut grade. These components are brightness, dispersion, scintillation, weight ratio, durability, polish, and symmetry.

When a diamond is graded, each factor is assigned a grade: Excellent, Very Good, Good, Fair, or Poor. The final grade is based on the lowest assessment in any category. For example, if a diamond’s lowest score were “Fair” in durability, despite ranking as “Very Good” in all other components, the final grade would be “Fair.”

Symmetry and polish are exempt from this rule, allowing a diamond with a “Very Good” polish to still rank as “Super Ideal.” Diamonds rated “Excellent” by GIA will fall under Ideal or Super Ideal on the Brilliant Earth site.

When Brilliant Earth evaluates a diamond, we use the GIA grading scale and specific diamond characteristics such as polish and symmetry to distinguish between Ideal and Super Ideal. In cases where the 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 difference in diamond cuts.

Diamond Cuts 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.
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 Diamond Cuts Affect Price

The cut is the foremost determining factor for the overall beauty of a diamond, so you can expect a higher grade to come with a more significant price tag.

Often, shortcomings in the clarity, color, and carat are offset by a beautiful cut. Masterfully crafted facets create incredible displays of light that mask inclusions and make the diamond appear larger than it actually is.

How Diamond Cuts Affect Sparkle

Sparkle, or the contrast between white light and the dispersed colored light within the gem, gives a diamond character. It's the wow factor that draws the eye from across the room, creating a dazzling display as the seemingly endless facets create a dance of light within the diamond.

When cutting a stone, careful attention must be paid to the complex interactions between the table, the crown's angle, the pavilion's depth, and the total depth. When properly calculated, with appropriate angles and well-defined proportions, the flashes of reds, blues, oranges, greens, and yellows enhance the gleaming, white brilliance.

Diamond Cuts FAQs

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.

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.
Types of diamond cuts include brilliant, step, and mixed. Brilliant cut diamonds have 58 facets for otherworldly sparkle. Step cuts add edges to the sides, creating a dazzling descent of light through the center. Mixed cuts combine the best of both worlds, with a step cut on the pavilion and a brilliant cut on the table.
A ranking of “Excellent” based on the GIA’s standards for a diamond cut is rare, as the gem must meet a demanding set of standards across seven components– brightness, fire, scintillation, weight ratio, durability, polish, and symmetry– to achieve this grade.
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.