What Are the Best Diamonds? The 4Cs of Diamonds

Emerald Cut

What are the best diamonds? Well, in order to ensure you are purchasing the diamond that best meets your needs, a basic understanding of the 4Cs (Color, Clarity, Cut, Carat Weight) of diamond grading is important. The grading scales, such as those introduced by the Gemological Institute of America (GIA) in the 1970s, determine their rarity and ultimately their value.


Let’s begin with the most objective of the Four Cs, carat weight.

The measurement that is used to describe diamonds smaller or larger than one carat is “Points.” 100 points equal one carat.

Diamonds are measured using very precise electronic scales because diamonds are priced by carat weight. So, 0.50 points represent one-half of a carat, 0.75 points is three-quarters of a carat, etc.

The physical weight is 0.200 grams about the weight of a paper clip.

“Total weight” refers to the combined total carat weight for jewelry with more than one diamond. For example, 20 diamonds in a single piece may be marked 1.23TW, or 1.67TW on the price tag which means all the diamonds together equal the total diamond weight in the piece.

There are many incorrect assumptions made about diamond carat sizes.
Do you think a two-carat diamond costs exactly twice as much as a one-carat? No. Rough diamonds that yield two-carat stones are far rarer, so if all other quality factors are equal, a two-carat stone will be more than double the price.


Another Frequently Asked Question is: What makes diamonds sparkle?

Of the Four Cs, Cut is the most important. It is man’s contribution to the natural beauty of a diamond. Two diamond crystals of the same carat weight may have the same clarity and color but one may not be as beautiful as the other if not cut to maximize its beauty.

Cut can refer to three things:

  • Overall shape: (i.e., round or marquise) and the facet arrangement; step-cut, brilliant-cut or mixed cut.
  • Proportions: meaning the angles, depths, and the relationship of the parts of a diamond to each other.
  • Finish: is the symmetry and alignment of the facets and overall polish (consistent size of facets that meet precisely.)

But before we talk about cut, it is important that we look first at the parts of a diamond. We are going to focus on the round brilliant cut, as it is by far the most popular. When a diamond receives grades of excellent for, polish, symmetry and cut on a GIA diamond grading report, the overall cut grade is TRIPLE EXCELLENT.

  • The crown is the top portion of the stone.
  • The largest facet, the table, is on the crown.
  • The girdle is the center of the stone.
  • The pavilion is the bottom portion of the stone and perhaps the most important in terms of cut. This cone-shaped pavilion acts as a mirror and if well-proportioned will reflect light entering the stone back to the viewer’s eye.

To see more about diamond proportions, click Here

The most popular diamond shape is the round brilliant. Brilliant-cut diamonds have 57 or 58 triangular and kite-shaped facets that highlight brilliance and fire. Diamonds with 57 facets have no culets.

Brilliant-cut diamonds can be shapes other than round, if fancy shapes feature kite and triangular-shaped facets then it is a brilliant cut. Four examples of fancy shapes: oval, pear, heart, and marquis feature this facet arrangement. Mixed cuts feature both triangular and straight facets.

In addition to brilliant-cut diamonds, there are also step-cut diamonds. Step Cut is a style of cutting with concentric rows of rectangular-shaped facets running parallel to the girdle. The most popular, most familiar, style of step cut is the emerald cut.

Emerald-cut is a step cut, many having 49 or 50 facets with 24 on top, 24 on the pavilion, 1 on the table, and 1 culet if there is a culet or keel line. Emerald cuts have beveled corners for both aesthetic and practical reasons. These beveled corners also provide a more secure setting edge for prongs.

If brilliant-cut diamonds highlight brilliance and fire, what does the emerald-cut highlight?

Emerald-cut diamonds show off clarity and color.
Baguette: Long thin step-cut (rectangular or tapered) used as accent stones.

“Princess cut” is a trade term that commonly refers to diamonds featuring square outlines and modified brilliant-cut facet arrangements. Since its debut on the jewelry market in the early 1980s, the princess cut has remained a popular alternative to the round brilliant because of its beautiful light display.

During the cutting process, less of the rough crystal is sacrificed when cutting a Princess compared to a round. Therefore, Princess cut diamonds tend to have lower price points than Round Brilliants.

The description of a cushion cut diamond is: A four-sided deep square or rectangle cut with rounded edges and large facets – it has a cushioned shaped girdle.

Why do we pay so much attention to cut? What is the benefit of an excellent cut?

The proportions are the relationships between the sizes of a stone’s various parts and angles. They are important in terms of the stone’s overall beauty, since they, more than anything else, determine the extent to which the stone can achieve its maximum potential in terms of its reflection of light, which translates into beauty.

A well cut diamond will exhibit the following three characteristics:

1. Brilliance
or brightness is the return of white light to the viewer’s eye (in the face-up position), light reflected from within the diamond as well as from the surface.

2. Fire is the breaking up of white light broken into its spectral colors. We normally see dispersion in the facets around the crown rather than through the table.

3. Scintillation
is “sparkle”. It is a display of reflections from the polished facets of the stone and is created by light and movement.

These three optical properties must be well-balanced in order to maximize beauty.

In a well-cut diamond, the facets on the pavilion act as mirrors. The light should enter the stone and be entirely reflected back out of the crown producing a beautiful and even distribution of light. If not, the stone will appear dull and lifeless.

The most widely used and recognized means of verifying a diamond’s quality is with a GIA Diamond Grading Report™, provided by the internationally recognized, nonprofit GIA (Gemological Institute of America).

A report from GIA provides an expert analysis of the quality of a diamond based on the 4Cs of diamond grading: color, cut, clarity and carat weight. The GIA Diamond Grading Report also includes a plotting diagram that depicts the diamond’s unique clarity characteristics. In addition, since GIA is not affiliated with any commercial enterprise, the public is assured of the world’s most impartial and accurate analysis of a diamond.

To learn more about diamond grading click Here

As mentioned in the video, your diamond may be laser inscribed with the report number found on the girdle. Laser inscriptions (If inscribed by GIA) are permanent; inscriptions benefit both the client and company by providing proof of origin, as well as ensuring a way to identify the diamond should it be lost or stolen. Each inscribed serial number is linked to a database that references the diamond’s information such as cut, color, clarity, and carat weight. This is an effective tool when clients need to repair, return or upgrade their diamond jewelry.


Clarity is described as blemishes on the surface of the diamond and inclusions which are characteristics found inside the diamond. Examples include:

Scratches: colorless lines on the surface of a diamond. Abrasions: series of minute scratches along a facet’s edge. Naturals:
a small portion of the diamond’s skin that is not polished

Included Crystal: a mineral crystal contained in a diamond. At 10x magnification, if the crystal looks like a tiny dot, it is called a pinpoint. If it looks like a small thin rod at10x, it is called a needle. Cloud: a group of minute crystals that diminish transparency. Feather:
a small break or fracture inside a diamond.

Diamond Clarity Plot:

Internal and external clarity characteristics-map of the diamond

Red ink used for internal characteristics –inclusions

Green ink is used for external characteristics – blemishes

Now that we know what we are looking for (inclusions and blemishes), what is used to look for them ( jewelers’ loupes and microscopes), let’s take a look at the actual grading scale.

The clarity grading system used by most gemological laboratories is the GIA scale, this is the most widely used grading scale in the industry; there are 11 clarity grades:

FL: Flawless, no inclusions nor blemishes under 10X magnification

IF: Internally Flawless, with only slight surface blemishes and no inclusions

VVS1-VVS2: Very, Very Slightly included, MINUTE extremely difficult to see under 10X magnification

VSI-VS2: Very, Very Slightly Included, MINOR difficult to see under 10X magnification

SI1-SI2: Slightly Included, NOTICEABLE easy to see under 10X magnification, and may be visible with the unaided eye I1-I2-I3: OBVIOUS inclusions visible to the naked eye, affects the beauty and may affect the durability

You should never see mounted diamonds graded FL and here is the reason why. By most standards, brands will not state a diamond is flawless after it has been set, because it cannot be guaranteed that during the setting process or later a surface blemish has not occurred, or that pressure exerted on the diamond during the setting process did not cause a minute feather. If either of these things happened and the stone was unmounted the clarity grade would be in question. So stones in jewelry would always be assigned the grade of internally flawless.

What factors do you think graders base their grades on when looking at inclusions?

Number– how many characteristics?

Size – how large or small are the characteristics?

Location – where are the characteristics located? Are they right in the middle, or to the side.

– what type is it? Example: cloud or a feather? Flat or three-dimensional and relief – how visible are the characteristics in contrast to the rest of the diamond?

Once a diamond grader looks at a diamond through the microscope, s/he then sketches the location of the inclusions onto what is called a clarity plot. A clarity plot is a map of the clarity characteristics present in a diamond.

The clarity plot is made up of two diagrams: the crown view and the pavilion view. The inclusions in a diamond are indicated on the plot based on their visibility at 10x magnification. Clarity plots always look much worse than the appearance of an actual diamond.

Clarity Value:

The rarest diamonds are at the top of the clarity scale and are more abundant as they grade lower down the scale. The higher on the scale, the more difficult it is to see the internal characteristics, even with the help of magnification.” All of these factors go to rarity and value.


Color is defined as the relative position of a diamond’s body color on a colorless to yellow or brown scale. Globally the GIA color grading scale is the most recognized called the D-Z scale which ranks diamond color beginning with ‘D’ for colorless moving down the alphabet to ‘Z’ for light yellow or brown.

Why do you think the D-Z scale starts with the letter ‘D’ and not with ‘A’? There are two reasons. The first is because ‘D’ is for diamonds. The second is because when the color grading system was developed at GIA, there were other grading systems that used terms like “grade A” or “grade B”. So in order to prevent people from confusing the GIA system with other systems in the industry, they differentiated themselves by starting with the letter ‘D’.

How does a diamond grader determine the color of a diamond? When we speak about color here, we are referring to the body color of the diamond, not the colors that radiate from the stone.

Diamond color is compared to diamonds of known color called “master stones.” These are comparison stones graded by the GIA and sold exclusively for color grading.

Since the type of light affects the way color will appear, diamond graders always use a northern-daylight equivalent light source. Brilliant cut diamonds are color graded with the table down, in order to avoid the internal reflections seen when the diamond is viewed in the face-up position, this approach makes it much easier to see the body color.

What is fluorescence?

Certain diamonds may exhibit a property known as fluorescence. Fluorescence is a natural phenomenon found in many diamonds and many colored gemstones. When exposed to ultraviolet light a diamond with fluorescence appears to glow, most often blue or white, to varying degrees. Fluorescence is rated as Faint, Medium, Strong, Very Strong.


Using high pressures and 1,000,000 pounds of pressure and 1300 degrees centigrade can actually rearrange the molecules within the diamonds to alter how they absorb or reflect the components of white light and thus altering the color the viewer sees. Lasers are used to drill into diamonds to create channels to introduce bleach that lightens and whitens dark inclusions, making them less visible.

Lab-created diamonds The first lab-created diamonds were seen in the 1950s, created by General Electric. These diamonds were industrial-grade, which was an important step forward towards the creation of commercial quality diamonds, that began to make their debut in jewelry in the 1970s.

But what exactly does Lab-created mean? what is the difference, between these and natural diamonds? Lab-created diamonds are born in laboratories. Scientists determined the exact heat and pressure to transform carbon into diamonds in crucibles that result in stones featuring the exact chemical, physical and optical properties. In other words, when tested, possess the same properties. Visually they are indistinguishable from natural diamonds with the unaided eye; experienced gemologists are needed to distinguish between them. It is curious to note that the first gem-quality synthetic diamonds were created in fancy colors. In fact, it took many years to create near colorless diamonds that were gem/commercial quality. Lab-created diamonds run from tiny stones to large stones up to 15 carats and larger. For more information on lab-created diamonds click Here

More and more these diamonds are becoming mainstream. Customers with sourcing concerns as well as the environmental impact of diamond mining see lab-created diamonds as a great alternative, without sacrificing the beauty of natural diamonds.


A fancy color diamond is a yellow diamond (or any color) that exhibits more color than the Z master stone or a diamond that exhibits any color of the spectrum. Fancy color diamonds are exceptionally rare. It is estimated that approximately 1 diamond crystal for every 10,000 is a fancy color.

There are three major causes of visible color in diamonds: trace elements, nitrogen = yellow, (in diamonds on the D-Z scale, nitrogen is also the cause of the various tints of yellow, but not in high enough saturation to be classified as fancy color)

boron = blue, hydrogen = purple; structural abnormalities, deformation of the atomic structure: pink and red diamonds and natural radiation = green diamonds. This is a fascinating topic and you can read more about this topic, by clicking Here.

In terms of value, fancy color diamonds cannot be directly compared to the pricing of diamonds on the D-Z scale. Each one is unique and supply and demand impact pricing more than on colorless and near-colorless stones.


What is the best diamond? As you have read here the top grades on the color, clarity, and cut scales are the rarest, the most valuable, and therefore the most expensive. In the top grades, the nuances between grades are so slight that they are difficult to discern, but prices will be dramatically different. But they may be just as beautiful if they are well-cut. One way to understand price differences is to research on sites such as www.bluenile.com Here you will find thousands upon thousands of loose diamonds with a multitude of Color, Clarity, Cut, and Carat weight combinations, all of which have diamond grading reports and that will be extremely helpful in finding the perfect diamond for you!

Thank you for reading my article. Please write your comments and questions below. I would also love to hear about what is most important to you when purchasing diamonds.

Francesca, G.G., F.G.A.

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