Being the most important factor among any diamond characteristics (including the 4Cs), diamond cut is the most characteristic you’ll hear and see while you’re searching for your perfect diamond.

Look at these two diamonds from Blue Nile, both are identical in terms of color, carat, and clarity, the left has an excellent cut, while the right one is only good:

Good vs Excellent cut BlueNile

You can clearly see the huge impact of the cut on diamonds! Although the price is around $500 between both, but it’s worth every cent on it (and will be a waste of money to get the right one actually).

Admit it, last time you visited a local jewelry shop, the jeweler tried to convince you getting a higher color or carat in order to have a better diamond, aka, more shining diamond.

On the other hand, diamonds experts & professionals will tell you the truth: Get yourself settled with a very good cut at least, and then look for other factors for your preference.

So, what is Diamond Cut? And why it’s the most controversial factor when diamonds are discussed? What are the grades in diamond cut chart and how every grade affects diamond light reflection?

It would be interesting to know that both diamonds hold “almost” the exact characteristics, except the cut, as we will see.

In this article you will understand in details why you MUST get a very good cut as a minimum (Excellent is recommended) in order to guarantee a great sparkle for your diamond, what are diamond cut grades, and we will also look quickly at the most popular diamond shapes as well because we have a separate article for diamond shapes.

What is Diamond Cut?

Diamond cut refers to the proportions of the parts of the diamond and how well the diamond reflects light. You know that sparkle that you see when looking at a diamond? Ever wondered why some diamonds sparkle more than others (you may see this referred to as diamond Brilliance).

Another example for diamonds with different cut, but now from James Allen with better imaging technologies:

Here is ad diamond that’s 1 Carat, H Color, and VS2 Clarity, a general look at the diamond characteristics might tell you that it’s a good one, but actually it’s not! Take a magnified look using 360-degree & 40x magnification by JA, do you spot any good brilliance?

Now compare it to this one, a very similar diamonds in terms of clarity, carat, and color, but way different in light reflection & brilliance, isn’t it?

That’s exactly the difference between a good cut diamond, and an ideal (Excellent) cut diamond! And this is what we’re going to cover in this post.

Diamond Cut and how it Affects Brilliance

Diamond cut refers to how the diamond was made (or got cut), it reflects also to how diamond facets are proportioned against each other, how diamond dimensions are well-proportioned, how the surface is polished, diamond depth & symmetry! 

Diamond Sparkle James Allen

All of these (and not a single factor of them) will determine how much of light will the diamond be able to reflect! The more reflection, the better performance, and this need higher cut grade!

When you look at a diamond and see a light reflection, this light is the reflection that goes off the diamond table mainly, and then off the facets on the crown, the more symmetric they are, the higher ability to reflect light, here is an image that shows different parts of the diamond for better consumption of this.

Diamond Anatomy


Most often than not (actually 9 times out of 10) a diamond that just doesn’t sparkle and has a bland look to it has a bad cut.

Do you know that of all the 4Cs, diamond cut is the one that has the greatest effect on the look of the diamond to the naked eye, wonder how and why?

A drop from VS1 to SI1 clarity or an F to H color (two grades differences) is almost never noticeable, however, a drop from Ideal to Good cut will often be noticeable to the naked eye because it will lack the sparkle one would expect.

And by the way, it’s a fact that no two diamond stones have the same characteristics, they might look the same under a lay man’s vision, but to gem professionals, it has been stated as a fact, that no two diamond stones are alike.

How Diamond Cut Affects Brilliance & Light Reflection?

Take a look at the image below, and notice how when a diamond is Cut to excellent & v.good proportions, light is refracted from one facet to another, then dispersed through the top of the diamond.

On the other hand, when a diamond is cut too deep, some light escapes through the opposite side of the diamond.

If the diamond is cut too shallow, light escapes through the bottom of the stone before it can be reflected.

In addition, the facets must be placed with precise symmetry for maximum brilliance.

Diamond Cut Light Reflection

Image courtesy of Taylor & Hart

The diamond cut is made up of a set of proportions including the diamond’s diameter, table, and crown. In total there are 7 measurements that contribute to the Cut but the 2 most important are Table and Depth. The Table is the large polished part of the diamond that faces up and the depth is the total.

What is Diamond Cut Grading Chart?

There are different grading systems to define diamond cut, but the most common & agreed-on one is the cut chart created by GIA since it’s known to be the best diamond certification lab.

GIA Cut Grading Chart categorizes diamond cut into 5 grades:

Poor, Fair, Good, Very Good and Excellent (called Ideal as well).

You might see a grade named Super Ideal at some stores like James Allen or Blue Nile, and we will see shortly more about this grade, but it’s worth mentioning that it’s not a grade defined by GIA.

JamesAllen Promo


The probability of the existence of these types of diamonds is uncertain. But these are diamonds that don’t reflect any light, all reputed online diamond stores like JamesAllen or Blue Nile do NOT sell poor cut diamonds.

Read: JamesAllen Vs. Blue Nile Detailed Review & Unbiased Comparison.


Not like they are ‘bad diamonds’, but they are not well-cut diamonds, and this affects their quality, they reflect as little light as possible, and even if you’re on a very low budget, we never recommend getting this grade, if you find it. because it’s very unlikely that you will find a fair cut on the known online stores.

If you’re on a very low budget, think of getting a lab-created diamond instead, but never ever get a fair cut diamond.

Since probably you won’t find a fair cut diamond on reputable online stores, always make sure to see & verify diamond certificate if you’re getting your diamond from a local jewelry store.


These diamonds are partially well-cut, based on the quality of sparkle that they give. They are cut in a way that they don’t lose their beauty or quality, they don’t reflect all the light that penetrates through them, but they are still not that cheap.

You can easily find good cut diamonds on all online merchants, but for us, it’s not a recommended grade to get, even the next grade in most cases, a good grade is NOT good in diamonds.

Read: Diamond 4Cs and Order of Importance

Very Good

These diamonds exhibit a higher cut and quality than the Good grade. They reflect a higher percentage of light; hence they sparkle more than the Good Grade, as a result of this, their worth and value are increased in the market.

Since we never recommend getting lower than this grade, it’s common to see this grade as the most budget-friendly grade (it’s still expensive though).

You either have to get v.good or excellent grade, while we always recommend trying to get excellent (ideal) even for lower carats, a lot of people go to v.good because it’s cheaper.

Always try to invest to get this grade (at least) more than any other factor, and always remember this image whenever you think of a good cut diamond.

Diamond Cut Light Reflection JPEG

Ideal (Excellent)

If you ask: What is the Best Diamond Cut, definetly this is the asnwer, the Ideal cut is always the best to get, try never to get any lower than this, even in favor or a lower carat, always seek the best cut possible.

Ideal & Excellent terms are used interchangeably in diamonds online stores & merchants, but in terms of diamond certificates, AGS considers Ideal as the grade above excellent (which we will see shortly), GIA doesn’t define any grade higher than Excellent.

Diamonds of this grade have a combined force of brilliance and fire; they sparkle and shine effortlessly, and also reflect most of the light that penetrates through the crown.

Symmetry & proportions (even Hearts & Arrows) of this grade are set to the most ideal figures, leaving a very small difference for the next grade when these metrics have reached the maximum.

Here are images for two diamonds we found on Blue Nile, both have almost identical characteristics, except the cut, the left is very good (link), and the right one is excellent (link), you can clearly spot the difference between these two grades:

Since around 3-5% only of global diamonds make it to this grade, it’s now too obvious why they are expensive.

Super Ideal

A combination of Scintillation, Fire, and Brilliance, these diamonds are the pride of every cutter and jeweler.

They are superbly cut and ranks the highest in the diamond grading, different online vendors refer to such grade in their own trademarked terms, so, for example, JamesAllen offers this grade as TrueHearts™, while Blue Nile names them Astor By Blue Nile, and you can see A CUT ABOVE grade on Whiteflash. Feel free to read the linked articles to have a better idea about these collections.

Blue Nile Ring

With these types of diamonds, light reflection is as impossible as anything, but remember that this grade is not defined by GIA, so don’t expect to see this grade on a GIA certificate for a TrueHearts diamond for example.

The 60/60 Diamond Cut Rule of Thumb

The most basic rule of thumb when looking for a round diamond is the “60/60” rule. What this rule states (it’s really more of a general guideline than a rule) is that you should look for a diamond with a table of 60% and a depth of 60%.

Before you take this rule for granted, we encourage you to read more about the Ideal Table & Depth percentages.

Each diamond shape has its own proportions that are considered best, but round diamonds are the only ones that are defined on the diamond certification.

Whiteflash A-CUT-ABOVE-Hearts-and-Arrows-Diamonds

Unlike the 60/60 rule of thumb we mentioned above, the GIA and AGS diamond cut grading systems take into the total proportions of the diamond.

Both labs may give a diamond an Ideal grade even one of its parameters may be slightly higher or lower than what one would normally consider Ideal if another proportion compensates for this (AGS doesn’t even give a 60/60 diamond its highest grade).

Basically, both AGS and GIA allow for mixing it up a little more than they used too and rely on actual return of light measurements rather than hard numbers.

To sum it up, while we often recommend going with the lowest eye-clean diamond clarity like an SI1 or lowest diamond color you are fine with it, so when it comes to cut we would recommend spending more for the better quality and going for the highest you can afford.

What Makes a Diamond Cut Grade? Types of Diamond Reflection

What determines the quality of the diamond Cut? In other words, what makes an artisan professional in creating a perfect cut from another mid-pro artisan?

We’ve said a before that Cut is the most influencing factor in light reflection through a diamond, when a diamond is cut to ideal proportions, the light gets reflected very well, on the contrary, a poor cut results in light going through the diamond and exits from the other sides.

That’s why we always insist on investing the most on an ideal or at least very good cut, more than any other diamond characteristic.

The quality of the cut of a diamond is determined by the following three types of light reflection. When a diamond is exposed to light, it reflects in the following ways:

  • Brilliance

The most seen type, it’s the white light that we see when we look at a diamond, it’s the light that goes to the diamond, and then reflect back to our eyes as we described in the image above.

But to be more accurate, light doesn’t go from the top, goes to a facet, then to the opposite one and goes back, not at all, if that’s the case, the reflected light will be minimal.

When light enters a diamond and hits a facet, it keeps bouncing off between mirror-like facets endlessly, and this is what causes a great sparkle, to have a facet on the exact opposite of a facet that was just got hit by light.

Some very good/ideal Cut diamonds reflect light as white, the lights get into the diamond white, and leaves white, on the other side, and due to a less professional cut, the light reflects as rainbow, something like this image (image courtesy of Whiteflash, house of A CUT ABOVE diamonds):

Diamond brilliance white

  • Fire

This is a myriad of color that reflects when light penetrates the crown of the diamond. The light bounces around in the diamond and flashes the eyes in a myriad of colors.

Do you see the rainbow that reflects back from a diamond? This is what Dispersion or Fire represents! It’s the rainbow of colors that reflects back to your eye when you look at a diamond. The Light; like the first left diamond in the last image, enters through the top, and it breaks down into a rainbow of spectral colors, then it’s reflected back and forth in the interior of the gem by bouncing off the mirror-like facets. So when it leaves the diamond (through the crown), it doesn’t get mixed with the entering light, rather, it stays like a separated line till it reaches the eye, in flashes of colors.

Diamond Rainbow reflection

  • Scintillation

Do you notice when you look at a moving diamond how light reflects through that? This is exactly what describes a scintillation, it’s the play of light that you see when you move the diamond against different light angles, and it’s demonstrated by sparkling on the diamond’s surface.

You can see it in the same image we used to demonstrate brilliance, the difference with scintillation is that scintillation appears when you move the diamond.

Diamond brilliance white

As you see in this image, when such a diamond is moved around the light, you can see different angles of reflecting color, a very good diamond cut will retain a good reflecting light when this happens.

Diamond Cut Vs. Diamond Shapes: What’s the Difference?

Ever wondered what’s the difference between diamond shapes & diamond cuts? You’re not alone.

There is some misconception about diamond cut, most people refer to diamond shapes as the cut, while it’s not, diamond cut is more about the symmetry, proportioning and polish of a diamond.

Where diamond shape is as it implies, the shape (that you can tell when you look at the diamond) of a diamond, whether it’s a Round, Princess, or others as we will see now.

Here we take a quick overview of the most common diamond shapes, if you want to the full review, feel free to read Diamond Cut vs. Diamond Shape & The Most Popular Shapes.

Popular Diamond Shapes

In the 1400s diamonds gained popularity in use as jewelry ornaments. During this time various diamond cuts and diamond shapes were developed. In 1919 Marcel Tolkowsky invented the Ideal Cut diamond, which quickly became recognized as the standard in round diamonds and the leader for use in diamond engagement rings. Below is a brief review of the most popular diamond shapes used today.

Round Shape Diamonds

Of these diamonds shapes, the most popular by far is the round diamond, which takes center stage in the classic engagement ring – a round, solitaire diamond set either in yellow gold or platinum. Shapes other than round are called fancy shapes. The most popular different round cut is the Ideal cut diamond which has 58 facets.

Learn more about round shaped diamonds

Shop for popular Round shape diamonds

Princess Shape Diamonds

Princess cut diamonds are the most popular of the fancy shaped diamonds. Princess cut diamonds are relatively new with a shape that is oblong, usually square or almost square, but with a modified brilliant cut arrangement of facets instead of a step cut. Most square or rectangular cuts just don’t live up to the round brilliant for sparkle, but princess cut diamonds are designed for getting maximum brilliance from a square cut.

Princess shape (along with round and cushion) can be cut to a perfect proportion that’s even more than excellent, which is called “Heart & Arrows” and some vendors have a separate collection for those, we came across some like True Hearts™ by JamesAllen, and A CUT ABOVE® by Whiteflash.

Shop for Princess Shape A CUT ABOVE® Diamonds on Whiteflash

Pear Shape Diamonds

Pear-shaped diamonds are a hybrid cut, combining the best of the oval and the marquise, shaped like a teardrop. Pear-shaped diamonds also complements a hand with small or average-length fingers. It works exceptionally well in pendants or earrings. 

Shop for Pear Shape diamonds on JamesAllen

Marquise Shape Diamonds

Marquise diamonds have an elongated shape with pointed ends supposedly inspired by the smile of the Marquise de Pompadour and commissioned by the Sun King, France’s Louis XIV. It is often used as a solitaire or enhanced by smaller diamonds. 

Shop for popular Marquise shaped diamonds.

Oval Shape Diamonds

Oval diamonds give an even, perfectly symmetrical design popular among women with small hands or short fingers. Oval diamonds have an elongated shape which can make a woman’s finger appear longer.

Shop for Oval Shape Diamonds on JamesAllen

Radiant Shape Diamonds

Radiant cut diamonds have a square or rectangular cut that combines the elegance of the emerald cut diamond with the brilliance of the round. Radiant cut diamonds have 70 facets to maximize the effect of its color refraction. 

Shop for Radiant Shape diamonds on JamesAllen

Heart Shape Diamonds

Heart-shaped diamonds are basically a pear-shaped diamond with a cleft at the top. Heart-shaped diamonds are sometimes considered romantic, but they can be difficult to cut. The skill of the cutter greatly determines the beauty of heart-shaped diamonds. 

Shop for Heart Shape Diamonds on JamesAllen

Trillion Shape Diamonds

The trillion cut was developed in the late seventies. The trillion cut is an adaptation of the radiant cut but it is in a triangular shape. The trillion is a triangle that has equilateral sides and is a combination cut of the step cut and the brilliant cut diamond. 

Asscher Shape Diamonds

Asscher cut diamonds were developed in 1902 by the Asscher Brothers of Holland. The Asscher cut is a stepped square cut, often called the “square emerald cut” and like an emerald cut, the Asscher cut has cropped corners. Asscher cut diamonds have gained in popularity recently. 

Shop for Asscher Shape Diamonds on JamesAllen

Cushion Shape Diamonds

The cushion cut diamond is an antique style of cut. Sometimes referred to as a “pillow cut”, the cushion cut has an open culet (the bottom of the diamond) and a rectangular to square shape with rounded corners. The beauty of a cushion cut is the depth of the diamond. In the past most quality cushion cut diamonds were found only on the antique and estate market, today cutters are once again cutting these stones. 

Shop for Cushion Shape Diamonds on JamesAllen

Emerald Shape Diamonds

Emerald cut diamonds have a rectangular shape with cut corners. It is known as a step cut because its broad, flat planes resemble steps on a staircase. Inclusions and inferior color are more pronounced in emerald cut diamonds, so pay close attention to clarity and color grading. 

Shop for Emerald Shape diamonds on JamesAllen

Summary: Final Words on Diamond Cut

Diamond Cut is the single most important parameter that affects how your diamond looks to the naked eye, and in a nutshell, here is what we’ve covered in this post:

  • A GIA cut grade of “Very Good” is a great selection and offers a great sparkle. If you are looking for maximum brilliance you should consider getting the higher grade of “Excellent”. Unlike some minor upgrades (diamond color for example) going from Very Good to Excellent will offer a noticeable change (and price as well).
  • Vendors will often push for AGS Triple Zero or Triple Excellent grading from AGS.  In almost all cases this is overkill and will not offer a noticeable improvement over AGS Very Good grading. In keeping with my philosophy of paying for what you can see I don’t recommend upgrading to the Triple Zero.
  • Beware the independent diamond cut evaluation of online vendors for round diamonds- I have seen many online vendors list diamonds as Ideal but when checking the actual GIA or AGS certificate found that in fact they were not Ideal.
  • We always recommend getting your diamond from one the reputable online stores for a lot of reasons, like JamesAllen (best shopping experience), or Blue Nile (largest collection, side-by-side with JA on this)

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