Diamond Cut Explained (Critical Buying Tips)

Wondering what diamond cut is and how it affects the price of diamond?

Perfect, you're in the right place!

In this Learning Jewelry guide, you'll learn:

  • What diamond cut is
  • How cut of a diamond affects price
  • The different types of cuts for most diamonds
  • The different types of cut grades for diamonds
  • And our buying advice when it comes to considering cut
diamond cut explained and buying tips

As opposed to diamond clarity, a diamond's cut can affect the brilliance and fire in a diamond. A deep cut or "built up" diamond and flat cut diamond both lose light when reflected in the sun.

In our opinion, the cut of the diamond is the most important "C" in the 4C's of diamonds. Read this guide to get the skinny on what you need to know to make the best buying decision.

Brilliance may be one of diamond’s natural calibers but the cut will determine just how much a diamond’s beauty sparkles. Precisely cut diamonds shine marvelously as the angles let light pass through the crown (or the top) and back. You may have heard a few cuts like princess, emerald, cushion, etc.

However, don’t be fooled by the word “cut”- this complex process is more than just giving the diamond shape and has significant implications for the value and price of a diamond. In this guide, I’ll take you through the various cuts in a diamond, including quality and grade. As you read on, you’ll also get a glimpse of how important a diamond’s cut is to maximize the gem’s optical properties.

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What Is “Diamond Cut”?

A diamond cut may not necessarily mean its shape (although names like oval, pear, round, etc represent shape) but to some extent explains a diamond’s proportions like polish and symmetry. You can easily identify a great cut from a poor one by simply looking at the beauty of the diamond. In essence, this “beauty” entails brilliance, fire, and scintillation, all of which are crucial optical properties of any gemstone.

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Brilliance is the amount of light passing in and out of the diamond. A perfectly cut piece will have perfect proportions allowing maximum light to be reflected. Fire is the rainbow effect that gemstones exhibit when placed in a darker environment. Scintillation is the arrangement of light and dark facets sparkling when the diamond is subjected to conventional or rather office lighting.

What’s The Difference Between Cut and Shape?

A diamond’s cut is the dimensions of the diamond that dictates how shiny it becomes. In simpler terms, the more precise the cut, the better brilliance, fire, and scintillation (see above for definitions) your diamond will show. On the other hand, a diamond’s shape refers to the general appearance of the stone. A diamond’s shape is determined by the outline of its two-dimensional edges.

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How Does A Diamond’s Cut Affect Price

A diamond’s beauty and price are hugely dependent on the precision and quality of the diamond’s cut.

Producing facets that are in equal proportions is the key to having a sparkling diamond. For instance, in a brilliant round cut diamond, the 33 facets on the crown must be in equal proportions otherwise there will be leakage of light.

A poorly cut diamond will look dull even in higher carat weights or table sizes. Without brilliance and fire, a diamond’s value is lower than average. Since all the 4Cs have significant effects on the price of a diamond, focusing on the best cut has an important impact on the beauty of your diamond. If you really want a high-quality cut diamond, you may have to compromise the GIA Color or Clarity just to find the best-cut diamond.

What Are The Different Types Of Diamonds Cuts?

When picking the right diamond, it is important that you get to know which cuts give out the best. Here are some of the common cuts made from diamond roughs.

various types of diamond cuts on James Allen

Here you can see various types of cuts in JamesAllen.com.

Cushion Cut

A cushion cut has rounded edges and large facets, which maximize the brilliance of a diamond. Sometimes it can be hard to distinguish from other cuts depending on how pronounced that curves along the edge are.

Round Cut

This is probably the most common cut, especially in engagement rings. If you are looking for very specific components, most diamonds will fall under this category. Round cut diamonds have been produced over the years in a bid to bring out the most sparkle. Most top tier cut grades are only done in round cut diamonds.

Princess Cut

A princess cut has quite sharp corners, resembling a generally square shape. Princess cut diamonds will have a fiery brilliance when viewed from all angles.

Emerald Cut

An emerald cut diamond has rectangular facets and looks like a large open table. Since no two diamonds are the same, the length-width ratio may be different from diamond to diamond. The beauty of an emerald cut stone is that you’ll be able to easily identify inclusions, especially with SI2 stones or worse.

Marquise Cut

A marquise cut diamond is generally made to look long and as large as possible, resembling a shield-like appearance. A marquise cut diamond will make one’s finger look skinnier and longer.

Pear Cut

A pear cut diamond resembles a teardrop and like the marquise-cut, it will make your fingers appear skinnier. When browsing through pear cut diamonds, you should be aware of the bow-tie effect, a common defect with such cuts.

What Are The Different Diamond Cut Grades?

When viewing a diamond’s cut grade, it is advisable that you refer to GIA’s grading. Even though the institute is an independent entity, it is by far the most recognized and accepted among experts and industry specialists.

Here is how GIA’s grading looks like in terms of Diamond’s cut.

Excellent

Excellent cut diamonds have proportions that give the highest levels of brilliance and fire. Because the facets are so perfect, almost all light that passes through them is entirely reflected. In AGS certificates, such cuts are graded Ideal Cut.

In terms of cut grading, some companies may claim to have Super Ideal Cuts, Excellent Ideal Cuts or any other acronym before the term Ideal Cut. These are cut grades assigned by the retailer NOT the grader like GIA or AGS. They're more of a marketing gimmick in my opinion versus an actual level of cut. Such diamonds may have surpassed the Excellent cut grade with even higher levels of sparkle. A good example is Blue Nile’s Astor Ideal, which the BN claims that only 15 out of 10,000 diamonds make this cut.

what is super ideal cut diamonds (1)

Very Good

Very Good Cut diamonds have exceeding brilliance and fire. A great deal of light that passes through the diamond’s facets is reflected through the table. However, Very Good diamonds may have the same sparkle as those of Excellent grade, at least to the naked eye.

Good

Good Cut diamonds show tolerable levels of brilliance and sparkle. They’ll reflect enough light through the table to the viewer’s eyes. These diamonds may have lower price points since brilliance levels are not up to standards.

Fair

Diamonds in this grade don’t reflect much of the light that passes through. As a result, the fire and brilliance are massively cut down. Diamonds with Fair Cut grading may not be suitable for centerpieces but will fit perfectly as side stones in jewelry.

Poor

Poor Cut diamonds may not exhibit any brilliance, fire, or scintillation of any sort. Since the facets are disproportionate, light entering through the diamond passes at the bottom of the diamond.

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How To Determine Cut Quality

The cut of a diamond is typically influenced by three major factors which are symmetry, proportion, and polish. Ultimately, each of these factors has an effect on a diamond’s fire, brilliance, and scintillation. Let’s find out how these factors stack up on the quality of a cut:

Proportions

The proportion of a stone’s cut entails the relationship between the angle, shape, and size of each stone’s facet. These characteristics are mainly related to the internal properties of the stone. A well-proportioned diamond, for instance, will have each facet inclined at angles that maximize the amount of light passing through.

Polish

The polish grade of a stone dictates how smooth the facets look after cutting and polishing. For a glazed appearance, each facet must be keenly polished after the cutting process. This allows the stone to exhibit maximum brilliance. On the other hand, a polish may not affect the brilliance that much but a very good polish rating is good enough.

Symmetry

A symmetrical stone will have perfectly balanced facets with proper alignments. In case the facets are not symmetrical, the stone’s sparkle will be greatly compromised. Symmetry is examined by gemologists under a 10x microscope. The major areas of symmetry in a diamond include the conformity of the crown and the pavilion, and the positioning of the culet in relation to the table.

My Recommendation When It Comes To Diamond Cut

Firstly, it should be clear that a diamond’s cut is by far the most important of the 4Cs that’ll help you find the best selection of diamond. When you go to any diamond retailer, be careful with diamonds described as Excellent Ideal Cut, Super Ideal Cut or anything of that sort.

Why?

You’ll notice that the difference in cuts at the top tier grading is like the old apple to apple comparison. Before you get enticed, just make sure to check out the AGS or GIA grading report. For GIA Certified diamonds consider Excellent Cuts and in AGS Certified diamonds, Ideal Cuts are the best. Relying on the retailer’s grading system alone may have a lot of loopholes.

Apart from relying on AGS and GIA, you can also do some background research examining the stone’s varying proportions including all measurements and angles. It may seem a lot of work, but trust me, you don’t want to get ripped off thousands of dollars because of a single “Cut” mistake. If you’re shopping online, I recommend you head over to James Allen as you will be able to view any diamond with up to 20x magnification.

Ultimately, the cut will carry most of the baggage while looking for the best diamonds. A cut can hide inclusions, increase brilliance, mask secondary hues, and make your diamond sparkle! 

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