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Diamond Buying Guide

This brilliant gemstone radiates light to its viewer and represents love, beauty and commitment. A diamond’s cut, color, clarity and carat weight are the four attributes that determine its cost and overall value. Known as the 4Cs, these qualities are used by gemologists to grade a diamond and are important considerations when purchasing.

The 4Cs never apply exactly the same on any two diamonds: even diamonds with the same general grading can have different characteristics - every diamond is unique. 

ColorColorless, gray, blue, yellow, orange, red, green, pink, purple, brown and black
CareClean using steam and ultrasonic. At home, gently scrub with lukewarm soapy water and a soft toothbrush.
Moh’s scale of hardness10
Refractory Index2.42
A diamond has fire.

Diamond is the hardest known substance in the world. The largest diamond ever discovered, the Cullinan diamond was found in South Africa and weighed 1.33 lbs (3,106.75 carats).

The Anatomy of a Diamond

The Anatomy of a Diamond

The 4Cs of a Diamond

The 4Cs


The diamond’s weight is the only C that does not have an impact its beauty. One carat is based on the weight of a carob seed. The tiny seeds from a locust (carob) tree are amazingly consistent in weight and for thousands of years these seeds were used to balance gem scales. 

Measurement of a diamond’s weight, carat (abbreviated ct.), is one attribute considered in grading a diamond.  A carat is a unit of mass equivalent to 200 milligrams. This measure of weight is used for diamonds and gemstones. 

A diamond’s weight is commonly referred to as points. A carat is divisible by 100 points, each point is equivalent to 2 milligrams. 100, one-pointers (.01) are equivalent to one carat. On a price per carat basis, a one carat gemstone is significantly more expensive than multiple smaller gems that weigh the same amount. The larger the gemstone, the higher the price per carat. 

While a gemstone’s weight in carats correlates to its size, the cut of a gemstone has a significant impact on its perceived size. Two diamonds that are the exact same carat weight may appear to be different sizes based on their cut. When viewed from above, a shallower cut diamond will have a larger diameter and appear bigger than a deeper cut diamond, even though the carat weight is the same.  When comparing the size of two diamonds, consider not only the length and width, but also depth measurements in millimeters. 

A finished jewelry item will often have the abbreviation, CTW (carat total weight) indicating the weight of all of the diamonds added together. 

Diamonds that are a major carat size, for example 1.0 carat , are in high demand. Diamonds that are slightly below a major carat size typically cost less per carat. 


Diamond Measurement Reference

The quality of the cut of a diamond is very important; it is what gives a diamond its unmatched brilliance and fire. No matter what the diamond’s shape is, a well-cut diamond will have the exacting proportions, symmetry, and finish for optimal light dispersion - called its brilliance.

The quality of a diamond’s cut also has a significant impact on its value. Poorly cut diamonds often are sold for large discounts while a beautifully cut diamond will sell for a premium.

Researchers using objective scientific methods of measuring light performance have conducted studies to find the optimum proportions to enhance a diamond’s light performance, thus increasing its brilliance, dispersion and scintillation.

A diamonds optimum light performance.

Cut is the leading factor in a diamond’s light performance or brilliance. When properly cut to proportion, light that enters a diamond is reflected through the top of the diamond. A diamond that is too shallow or too deep allows light to escape out the sides or bottom of the diamond resulting in a dull diamond with less sparkle. 

A set of guidelines has been created based on this research. Each unique piece of diamond rough is evaluated by master gem cutters as they apply the guidelines to reveal the largest, most brilliant diamond possible.

There are three major components of cut; the diamond’s proportions, its symmetry and its polish. A well-cut diamond just explodes with light and fire. 

The edge or widest point on a diamond is called its girdle. A round brilliant has 32 facets and the table (large top facet) above the girdle – this part of the diamond is called the crown. Under the girdle there are 24 facets and the diamond’s culet or point – this part of the diamond is called its pavilion. A modern round brilliant cut diamond has a total of 57 facets with the possibility of 58 if the culet is faceted instead of pointed.

The diamond’s proportions are the relationship between the total depth (measured from the table to the culet), table, crown, pavilion and girdle and are expressed as a percentage of the diamonds average diameter.

The diamond’s symmetry refers to the exactness of the outline, placement, alignment and symmetry of the individual facets.

The diamonds polish is simply how well finished, smooth and free of polish lines and small blemishes the surface and individual facets are.

A standard round brilliant diamond’s overall Cut Grades, using GIA nomenclature are:

Excellent, Very Good, Good, Fair, Poor.

The most prevalent cut is the round brilliant. Because all the perorations, angles and facet placements are equal around the circumference or girdle of the diamond it is also, technically, the most brilliant - evenly distributing the maximum amount of light return.

This important attribute should not to be confused with a diamonds shape. Cut, as one of the 4Cs, refers to the ideal proportions of a diamond, to optimize light performance, along with its symmetry and polish. 

However the term Cut is often also used to refer to a diamonds shape and style as well as what is required of the cutter to create the symmetry, polish and proportions for that shape and style. 

The round brilliant cut is the most recognized style and shape - others are generally called Fancy

Fancy shapes include: Marquise, Princess, Oval, Cushion, Emerald, Pear just to name a few.

With fancy diamond shapes, a small amount of light return is often sacrificed for the art or style of the cut.

Cut has the greatest impact on a diamonds sparkle to it is frequently considered the most important attribute when choosing a diamond.


Colorless or white diamonds are the most recognized and a completely colorless (or pure white) diamond is treasured for its extreme rarity and beauty. 

Color grading is determining the diamonds body color divergence from completely colorless.  

When considering a white diamond, color, or more specifically the lack of color, impacts its value. The less color, the higher the color grade. 

When grading a diamond, gemologists view the diamond in a controlled environment where lighting and conditions are consistent. Gemologists use a set of Diamond Master Stones to compare against. The diamond is viewed next to the Diamond Master Stones in this environment to classify the diamond’s color.

The Color attribute ranges from D (colorless) to Z (light yellowish).

A diamonds color ranges from D to Z.

Keep in mind that each color grade is not a specific color or tint – it is a range of body color or tint. A diamond with a H color grade would have more color than a G and less color than an I – but two diamonds with an H color grade would not necessarily be the same exact color. The scope of each color grade increases as you go through the alphabet.

Fancy-color diamonds are yellow or brown diamonds that have more color than the Z Diamond Master Stone. They can also be diamonds that exhibit colors other than brown or yellow. Fancy colored gemstones are graded on a different color scale. 

Fancy colored diamonds beauty can occur in a rainbow of colors. A fancy colored diamond is a very rare and uniquely beautiful gem. Vibrant yellows, deep rich browns, greens, pinks, light to strong rich blues, orange, purples, black and the rarest of the rare...red! The most common fancy colored diamonds are the browns (sometimes referred to as champagne or chocolate diamonds) and yellows. 

For a diamond to be considered a fancy color it must have a body color that is greater than Z. Fancy color is graded by increasing strength from Faint, Very Light, Light, Fancy Light, Fancy Intense, Fancy Vivid, Fancy Dark and Fancy Deep

Detecting color in a diamond is more difficult when it is set into yellow gold.  


The clarity of a diamond is its fingerprint. Many diamonds have small internal or external irregularities or characteristics that were created when the crystal was formed or cut. These characteristics are called inclusions. The size, number, nature and position of these inclusions determine the diamond’s clarity.

In some cases surface blemishes and internal inclusions can alter the brilliance of a diamond.

Diamond clarity grading is done under 10X magnification using a specialized binocular microscope called a Gemscope.  

The Clarity scale ranges from Flawless (no inclusions or blemishes visible under 10X magnification) to Included (visible to the naked eye).  

A diamonds clarity determines its brilliance.

(FL) & Internally Flawless (IF) - No inclusions visible under 10X magnification.  

VVS 1 to VVS2 - Inclusions are difficult to locate or see at 10X. 

VS1 to VS2 - Inclusions less difficult to see or locate under 10X.  

SI1 to SI2 - Inclusions readily seen at 10X, but remain invisible to the unaided eye when the diamond is viewed face up.  

I1 - One or more inclusions, or their effect, can be seen by the unaided eye.  

I2 - Inclusions are so obvious that they affect both the brilliancy and beauty of the diamond.  

I3 - Shattered appearance or vivid disfiguring and dangerous inclusions and surface marks.  

Just like with color grading each clarity grade is a range between the preceding grade and the grade immediately following. The scope of each clarity grade increases as you go down the scale.

After purchasing a diamond, you’re unlikely to look at it under magnification. Purchase a diamond that is eye clean.

 Advanced issues found

Tips from our experts

Stay within budget and invest in the attributes that are most important to you.

The first three rules of diamond buying are cut, cut, cut.  Choose diamonds that are Very Good (VG) or better. 

Pay for what you can see, not for what you can’t.  Most people don’t begin to see color until G.  Most SI1 diamonds are eye clean.  

An inclusion located near the edge, or girdle of the diamond, may be hidden during the setting process by placing it under a prong.

If during the purchase process you see an inclusion with the naked eye, from that moment on you’ll see it. 

All diamond certificates are not created equal.  GIA and AGS are the gold standard for diamond grading.

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