Diamond Cuts: Education to Avoid Getting Ripped Off [2021]

diamond cuts

If there are two things many people get confused about when buying diamonds, they are cuts and shapes. You hear these terms a lot, but they are often used interchangeably, thus the confusion.

Diamond cuts and shapes are factors that have two completely distinct definitions. People often think a diamond’s cut is how it is shaped – rounded, oval, marquise, or pear. In reality, the cut is how well a diamond’s facets interact with light.

Appreciating a diamond’s beauty, shine, and symbolism is more than just looking at the size and the shape. Diamond’s cut is one thing you should understand to get the best diamond and not get ripped off.

What Is A Diamond Cut?

A diamond cut is clear-cut artistry and craft required to transform a stone to make its proportions, symmetry, and polish bring the resplendent return of light that is only possible in gemstones like diamonds.

Pulling off the best cut for a diamond allows it to showcase its absolute beauty and value. Out of the four Cs of diamonds, a cut is the most complicated and technically arduous to analyze.

GIA (Gemological Institute of America) calculates the proportions of the facets that impact the diamond’s face-up appearance to determine the cut grade of a standard round brilliant diamond. These sections permit the GIA to appraise what the best cut for the diamond is.

Diamond’s cut is graded based on how well it interacts with light to give off the sought-after visual effects such as:

  • Brightness
  • Fire
  • Scintillation

Brightness is the internal and external white light that is reflected from a diamond. The second visual effect – fire is the scattering or dispersal of white light into all the rainbow colors. The last visual effect, scintillation, is the sparkle from the diamond caused by the reflections within it.

Diamond Cut Quality Grading for Round Diamonds

Diamond cutting grades for round diamonds stretch from Excellent to Poor. Grading is based on some considerations that include symmetry, polish, brilliance, and fire. To get the most brilliant and beautiful, consider brilliant round diamonds with Excellent cut and ensure that the symmetry and polish are either Excellent or Very Good.

The truth is, 55% of round diamonds receive an Excellent cut grade from GIA. But, about 25 to 30% of these are not recommended. The reason is consultants review thousands of Excellent cut diamonds and discover wrong specs from its depth, table, and angles.

This is why it is essential to check the diamond cut grade on the GIA certificate and go over the diamond closely by yourself or with an expert. You wouldn’t want to waste your money with an “Excellent” diamond that is, in reality, only an average stone.

To get a better understanding of the diamond cut quality grading, here is a chart the professional gemologists at the GIA bases their reviews for each diamond under magnification:

Grade Meaning
Excellent excellent grade Delivers the highest fire and brilliance level since almost all of the incoming light is reflected through the table. This makes the diamond radiate with magnificent sparkle.
Very Good                 very good Provides incomparable brilliance and fire. A large margin of the entering light reflects through the diamond’s table. To the naked eye, they offer a similar sparkle to those of Excellent Grade.
Good                 good Showcases brilliance and sparkle with loads of light reflecting through the table to the viewer’s eye. Diamonds in this cut grade provide beauty at a lower price point.
Fair                 fair Offers little brilliance. The light smoothly transits through the bottom and sides of the diamond. They are a good choice for smaller carats and those standing-in as side stones.
Poor                poor Yields close to no sparkle, brilliance, or fire. Light entering escapes from the sides and bottom of the diamond.

AGS (American Gem Society) has on their diamond cut grade chart “Ideal” score. For this agency, grading is – Ideal, Excellent, Very Good, Good, Fair, or Poor. We recommend going only for diamonds rated Ideal when looking at AGS diamonds.

Is the Ideal cut rating of AGS the same as the Excellent cut rating of GIA? Blue Nile also uses the term Ideal in their round brilliant diamond cuts. These two terms are interchangeable in representing the cutting style, proportions, and finish.

How Diamond Cut Grade Affects Diamond’s Price

Prices of diamonds are dependent on the precision and quality of the cut – mainly its proportions and symmetry. However, other facets affect the cost of the diamond, too.

Light Effect on a Diamond

The extent of light return and brilliance found in an outstandingly cut diamond is worth the extra bucks in its price. Numerous factors affect the diamond’s brilliance, wherein the most crucial factor is its ability to reflect light. Light has three different effects on diamonds, and they are:

  • Reflection – happens when the light enters the surface of a diamond and a portion of it is reflected out of the table.
  • Refraction – is when the remaining rays of light travel into the diamond’s center and bounce off its internal walls.
  • Dispersion – happens as the light exits the diamond. This effect caused the white light to be separated into multiple colors.

Diamond Proportions

Diamond proportions, primarily its table, width, and depth, are elements universally measured. They serve as magnificent indicators of diamond’s cut quality. This factor directly affects a diamond’s ability to reflect light and providing brilliance.

Depth is essential in diamond proportion. It is the height of the diamond in millimeters measured from the table to the cullet. Depth substantially impacts the quality of a diamond’s cut and the amount of light it reflects.


Even with a flawless clarity grade, Diamonds may still look glassy or dull if the cut does not conform to the right diamond proportions. Therefore, the best cut grade you can afford is still a worthy diamond to buy. Here’s how the Blue Nile illustrates the best diamond proportions.



Diamond’s table is its flat surface facet. The large surface you can see when you look at it from above plays a critical role in the diamond’s appearance. This part of the diamond refracts rays of light as they pass, leading them to the facets that make them look sparkly and brilliant.

Bigger is not always better when it comes to the diamond’s table. A massive table on the diamond leaves the crown’s upper facets not having room enough to disperse light. Likewise, a very small table may simply diminish its overall brilliance since there won’t be much light getting into the stone.

The ideal table percentage rests deeply on the diamond shape.


The depth (the diamond’s height) is the distance between the table and the cullet (the diamond’s pointed tip). Similar to the diamond’s table, the gemologist grades the depth according to its depth percentage.

The depth percentage of a diamond is its depth divided by the width of the diamond. The result dictates the overall proportions of the stone. Accordingly, it contributes to the impact of how light reflects off the facets of the stone.

Since the diamond’s depth weighs into the diamond’s sparkle significantly, if the cut is too shallow, the light will easily pass through the pavilion or the lower half of the stone without any reflection. On the contrary, a cut too deep will result in poor sparkle. It will also make the stone appear smaller than other stones of the same carat.


To determine the diamond’s width, you should measure from one end of its girdle or the diamond’s diameter at its widest point up to the other end of the girdle. Width is essential in finding out the length to width ratio. This figure signifies how proportionate the diamond is along with its shape.

Symmetrical Facets

The tiny mirrors that reflect light to your eyes when you look at a diamond are the facets. They are the small sides that surround the diamond’s table. Facets are also found above and below the girdle, meaning the pavilion is made up of facets. A round brilliant diamond is cut with a total of 58 facets.


The diamond’s brilliance is its brightness of the white light reflection. When faced up under a light, a perfect cut diamond should reflect an abundance of white light. Without symmetry, or if the diamond is too deep or too shallow, it will look dull rather than brilliant.


When you look at a diamond, you will see colored lights that reflect and bounce off the table and facets. These colored lights are the diamond’s fire. Well-cut diamonds do not only reflect white light radiantly but produce fire, too.

The best way to witness the diamond’s fire is during daytime and in daylight. The daylight lets you see colored lights bouncing off the facets of the diamond. If it doesn’t display colored light reflection, then it has a low amount of fire.


The diamond’s scintillation is the flashes of sparkle when light moves on the facets and table. It is the scattering of light that resembles a spark. Scintillation is caused by the light and dark areas on the diamond’s surface. A diamond with vast amounts of scintillation is more attractive.

Finishing Details

The craftsmanship of a diamond is its permanent treatment and polishing. Polish refers to the condition and quality of every facet. A well-polished diamond produces a clear mirror for light to reflect off of. Contrarily, less-polished diamonds look dull because the facets can’t reflect light as intensely.

Diamond’s Cut and Shape – What is the Difference?

As previously stated, cut and shape are two different things when it comes to diamonds. Many people are confused with these two terms, but let’s clear it up once and for all.

Diamond shape refers to the outline or the figure of the diamond. For instance, pear-shaped, heart-shaped, or round brilliant. They all tell the appearance that you should expect – how they look and, literally, how they are shaped.

The cut is a whole different story. It is the diamond’s facets, symmetry, dimensions, and reflective quality rolled into one. For example, your heart-shaped diamond can have a shallow or deep cut, could be dull or brilliant. The shape remains as it is, but the cut may differ considerably.

To put it simply, no matter what shape it is, the brilliance, fire, and scintillation that most people look for in diamonds are still brought by the diamond’s cut.

Conclusion: Buying the Right Diamond

It is highly recommended to look out for a quality diamond cut more than anything else when buying a diamond. For GIA Diamonds, go for the Excellent cut. Likewise, for AGS Diamonds, an Ideal cut is recommended.

James Allen’s diamond search helps if you need to filter your search heavily leaning on diamond cut. Brian Gavin’s Signature cut offers maximum brilliance. After all, they are the leading industry expert in the cut optimization field.

Make sure to consider symmetry and polish as they have a considerable impact on the cut grade.

If you are on a budget but are heavily concerned with the diamond size, a Fair cut grade is your acceptable choice. They go really well with fancy shapes. Although it may lack the scintillation and brilliance of a well-cut diamond, it will let a considerable increase in size for the same amount.

Never go for poor cut diamonds at all costs, even when size is your primary concern. These diamonds are found to be unacceptable trade-offs despite the lower price.

FAQs (Frequently Asked Questions)

Q: What is the most expensive cut of diamond?

A: Everyone focuses on the carat when someone shows off their engagement ring. It is the cut of the diamond that has the most significant factor in the price tag. The market today has Blue Nile’s Ideal Cut diamond as the most expensive cut. They proved to have optimized light performance and created the most remarkable sparkle.

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