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Diamond Education

The 4Cs Of Diamonds

This short tutorial explains the 4Cs of Diamonds - cut, color, clarity, and carat weight. These are the most important characteristics to understand when making a diamond purchase.

What makes a diamond valuable?

In the diamond industry, the four c’s of buying a diamond: carat, color, clarity, and cut are known as diamond value factors and affect a diamond's price.



Clarity refers to the presence of identifying characteristics on and within the diamond. While most of these clarity characteristics are inherent qualities of the rough diamond, a few clarity flaws are actually a result of the stress that a diamond undergoes during the cutting process. Diamonds with no or few inclusions and blemishes are more highly valued than those with less clarity, not just because they are more pleasing to the eye, but also because they are very rare. Diamonds are graded for clarity under 10x loupe magnification. Clarity grades range from Internally Flawless, diamonds that are completely free of blemishes and inclusions even under 10x magnification, to Imperfect 3, diamonds which possess large, heavy blemishes and inclusions that are visible to the naked eye. Clarity categories include: 

FL:  Completely flawless

IF:  Internally flawless; only external flaws are present, which can be removed by further polishing the stone

VVS1 – VVS2:  Only an expert can detect flaws with a 10X microscope. By definition, if an expert can see a flaw from the top of the diamond, it is a VVS2. Otherwise, if an expert can only detect flaws when viewing the bottom of the stone, then it is a VVS1

VS1 – VS2:  You can see flaws with a 10X microscope, but it takes a long time (more than about 10 seconds)

SI1 – SI2:  You can see flaws with a 10X microscope

I1 – I3:  You can see flaws with the naked eye. Consider avoiding I2-I3 diamonds.

For grades IF through SI, a diamond’s clarity grade has an impact on the diamond’s value, not on the unmagnified diamond’s appearance. While Flawless diamonds are the rarest, a diamond does not have to be flawless to be valuable. There are many different types of flaws. The more common ones are:

Pinpoint:  A very small white dot on the surface of the stone (most common flaw)

Carbons:  A very small black dot on the surface of the stone. Less common than pinpoints

Feathers:  Small cracks within the stone, similar in look to broken glass. Small internal feathers are harmless (other than lowering the clarity rating of the diamond), but large feathers can become a problem because the crack can grow as the diamond ages

Clouds:  Hazy areas within the diamond, actually made up of many small crystals that are impossible to see individually

Crystal Growth:  A small crystalline growth within the diamond. Looks like a small diamond within the big diamond

Clarity is very difficult to judge accurately by an inexperienced consumer. A VVS1 diamond and an SI2 look exactly the same to the naked eye. If you’re purchasing an emerald or any other step cut, consider purchasing a diamond with clarity greater than SI1. Clarity flaws are much more readily visible in step cuts than in brilliant cuts.



A diamond’s color is graded on an alphabetical scale from D-Z to describe how much or how little color a diamond possesses. The best quality diamonds and the most valuable ones are completely colorless. Very few diamonds reach this standard. A Colorless diamond is perfect or almost perfect in color. G-J  Near-colorless: good to very good color, and this diamond may “face-up” colorless when mounted. K-M Light but noticeable yellow or brown tint. May “face-up” colorless when mounted, especially when mounted in yellow gold.


While many diamonds appear colorless, or white, they may actually have subtle yellow or brown tones that can be detected when comparing diamonds side by side. Diamonds were formed under intense heat and pressure, and traces of other elements may have been incorporated into their atomic structure accounting for the variances in color. A single change in color grade can significantly affect a diamond’s value. Although the presence of color makes a diamond less rare and valuable, some diamonds come out of the ground in vivid ‘fancy” colors — well-defined reds, blues, pinks, greens, and bright yellows. These are highly prized and extremely rare.



Carats are the traditional measuring unit of a diamond’s weight, one carat equaling 200 milligrams. A carat is divided into 100 “points,” so the same diamond can be represented as weighing a carat and a half, 150 points or 1.50 carats. With each weight category increase (quarter, third, half), the value per carat of a diamond will increase significantly (given all have the same other factors).


The round brilliant cut is designed to provide maximum optics for the brilliance and scintillation, making the light seem to sparkle and dance in the stone. A deeply cut stone will also affect the way the light passes, which is reflected in the mass of the diamond. Fancy cut stones (marquise, emerald, pear, princess, and triangular cuts) are all variations of cutting a stone to maximize the carat weight by the cutters, a rough diamond which might only yield a half carat in a round shape might yield another 50% if cut into a pear shape or marquise. Many of the fancy shapes are stunning, but all fancy cuts sacrifice maximum brilliance for that specialty cut to some degree.



When a diamond certificate says “cut,” that’s a reference to the diamond’s reflective qualities, not the shape. Shape refers to the general outward appearance of the diamond (such as round, emerald, or pear). Diamond cut is perhaps the most important of the four Cs, so it is important to understand how this quality affects the properties and values of a diamond. A good cut gives a diamond its brilliance, which is that brightness that seems to come from the very heart of a diamond. The angles and finish of any diamond are what determine its ability to handle light, which leads to brilliance. Because cut is so important, several grading methods have been developed to help consumers determine the cut of a particular diamond. In general, these grades are:

Ideal:  This cut is intended to maximize brilliance, and the typically smaller table sizes of these diamonds have the added benefit of creating a great deal of dispersion or ‘fire’ as well. Ideal quality diamonds are truly for the person who enjoys knowing that he has one of the finest things that money can buy. This category applies only to round diamonds.

Premium:  In the case of round diamonds, many Premium Cut diamonds have cuts that are equal to any Ideal Cut diamond, though they often can be purchased at slightly lower prices than AGS Ideal Cuts. They are intended to provide maximum brilliance and fire. Like the Ideal Cut, these are also for the person who enjoys knowing that he has one of the finest things that money can buy.

Very Good:  These diamonds reflect most of the light that enters them, creating a good deal of brilliance. With these diamonds, the cutters have chosen to stray slightly from the preferred diamond proportions in order to create a larger diamond. Generally, the price of these diamonds is slightly below that of Premium cuts.  Represents roughly the top 15% of diamond quality based on cut.

Good:  Diamonds reflect much of the light that enters them. Their proportions fall outside of the preferred range because the cutter has chosen to create the largest excellent cost savings for customers who want to stay on a budget without sacrificing quality or beauty. 

Fair & Poor:  A diamond graded as fair or poor reflects only a small proportion of the light that enters it. Typically these diamonds have been cut to maximize the carat weight over most other considerations. Most of these types of cut diamonds can be found in retail mall jewelry stores. 


GIA Certification

Every loose diamond is accompanied by a GIA grading report. Independent diamond grading labs abide by stringent grading and certification guidelines.GIA laboratory issues diamond grading reports for loose, natural diamonds in the D-to-Z color range that weigh 0.15 carats or more. GIA Diamond Grading Reports are not issued for laboratory-grown diamonds, diamond simulants, mounted diamonds, or those that have undergone unstable treatments, such as fracture filling or coating. Reports may be issued for diamonds that have been laser drilled or HPHT processed, reports will indicate that the diamond has been treated.