Learning about diamonds is first understanding the ‘Four C’s’ which are judged to distinguish the diamonds from various significant grades and class.
Why are the ‘Four C’s’ important to understand? Well, they are used worldwide to organize the rarity of diamonds. Diamonds with the blend of the highest ‘Four C’ ratings are rare and far more expensive

• Cut
• Clarity
• Color
• Carat weight

These are the principles, jewelers use while grading diamonds and these are features that you will have to understand when you go ahead to buy them.

The First C- Cut

Cut is possibly the most essential and most demanding of the Four Cs to understand. The radiance of a diamond depends heavily on its cut.
Never confuse the diamond’s 'cut' with 'shape.' Shape always refers to the general outward appearance of the diamond, (such as square, emerald, round.). When a diamond jeweler says 'cut,' that's in reference to the diamond's reflective qualities and not the shape.

It is important to understand how ‘cut’ affects the properties 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 determines its ability to handle light, which leads to brilliance.

As shown in the images below, when a diamond is well-cut, light enters through the table and travels to the pavilion where it reflects from one side to the other before reflecting back out of the diamond through the table and to the observer's eye.

This intensity is what creates a fiery effect that makes diamonds so very enchanting.

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In a poorly cut diamond, the light that enters through the table reaches the facets and then 'leaks' out from the sides or bottom of the diamond rather than reflecting back to the eye. Less light reflected back to the eye means less brilliance.

Good Proportion is the Right Solution.

Most gemologists agree that the best cut diamonds are those that follow a set of formulae planned to maximize brilliance. These formulae can be seen in a diamond's magnitudes, most importantly how the depth compares to the diameter, and how the diameter of the table compares to the diameter of the diamond.

Today, several grading methods have been developed to help consumers determine the cut of a particular diamond. In general, these grades are

• Ideal
• Premium
• Very Good
• Good
• Fair & Poor

Which Grade Should I purchase?

Selecting the grade of cut is really a matter of inclination. To make the best selection, you need to understand the various grades. Please note that the descriptions below are general guidelines.

Ideal Cut

This cut is anticipated 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 the equal of 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. The result is that these diamonds fall slightly outside of some customers' preferences in terms of, for example, table size or girdle width, though, in many cases many of the parameters of diamonds in this assortment will overlap with certain parameters of diamonds in the Ideal or Premium ranges. Generally, the price of these diamonds is slightly below that of Premium cuts.
 
Good

Diamonds that 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 possible diamond from the original rough crystal, rather than cutting extra weight off to create a smaller Premium quality diamond. Diamonds in this range offer an excellent cost-savings to customers who want to stay in 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.

Diamond Anatomy

Crown, Girdle, Pavilion….unfamiliar terms to you? The graphic and the supporting text below explain the various 'parts' of a diamond.

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• Diameter The width of the diamond as measured through the girdle.
• Table This is the large, flat top facet of a diamond.
• Crown The upper portion of a cut gemstone, above the girdle.
• Girdle The narrow rim of a diamond that separates the crown from the pavilion. It is the largest diameter to any part of the stone.
• Pavilion The lower portion of the diamond, below the girdle. It is sometimes referred to as the base.
• Culet The tiny facet on the pointed bottom of the pavilion, which is the portion of a cut gem below the girdle.
• Depth The height of a gemstone, from the culet to the table.

The Second C- Diamond Clarity

When we speak of a diamond's clarity, we are referring to the presence of identifying characteristics on (blemishes) and within (inclusions) the stone.

If you think about the incredible amount of pressure it takes to create a diamond and the fact that natural diamonds are not grown in a laboratory, it's no surprise that most diamonds have flaws.

Basically there are two types of flaws: inclusions and blemishes. Inclusions refer to internal flaws and blemishes refer to surface flaws. However, in the diamond grades listed below, you'll note that none of the grades include the term 'blemish' -- for the purposes of grading diamonds, all flaws are called 'inclusions.'

Inclusions include flaws such as air bubbles, cracks, and non-diamond minerals found in the diamond. Blemishes include scratches, pits, and chips. Some blemishes occur during the cutting processes (most often at the girdle). Diamonds with no or few inclusions and blemishes are more highly valued than those with less clarity because they are rarer.

How Are Diamonds Graded For Clarity?Diamonds are graded for clarity under 10x loupe magnification. Grades range from Flawless (diamonds which are completely free of blemishes and inclusions), to Included 3 (diamonds which possess large, heavy blemishes and inclusions that are visible to the naked eye).

• F
  Flawless: No internal or external flaws. Extremely rare.
• IF
  Internally Flawless: no internal flaws, but some surface flaws. Very rare.
• VVS1-VVS2
  Very Very Slightly Included (two grades). Minute inclusions very difficult to detect under 10x magnification by a trained gemologist.
• VS1-VS2
  Very Slightly Included (two grades). Minute inclusions seen only with difficulty under 10x magnification.
• SI1-SI2
  Slightly Included (two grades). Minute inclusions more easily detected under 10x magnification.
• I1-I2-I3
  Included (three grades). Inclusions visible under 10x magnification AS WELL AS to the human eye. We do not recommend buying diamonds in any of these grades.

While the presence of these clarity characteristics, do lower the clarity grade of a diamond, they can also be viewed as a proof of a diamond's identity. GIA certificates include what is known as a “plot” of a diamond’s inclusion -- think of it as a 'diamond fingerprint.' Since no two diamonds are exactly the same, comparing the uniqueness of your diamond's clarity characteristics with the plot provided on the diamond certificate offers assurance that the diamond you pay for is the same diamond you receive.

Which Clarity Grade Should I Go For?

Mostly Flawless diamonds are the rarest, a diamond does not have to be flawless to be stunning.

In fact, until you drop to the 'I' grade, a diamond's clarity grade has an impact on the diamond's value, not on the unmagnified diamond's appearance.

Diamonds with VVS and VS grades are excellent choices for both value and appearance.

More reasonable and a great choice are those diamonds which gemologists call 'eye-clean' - diamonds with no inclusions visible to the naked eye. These diamonds are SI1 and SI2 and unless the recipient carries a 10X loupe i.e. a strong jewelry magnifying glass, one won't see the inclusions.

As to I1-I3? Maybe when there's a diamond grade that's defined as 'you can see the flaws just by looking at the diamond,' nothing more needs to be said.

But if you choose to buy an I1-I3 diamond, know that some people will look at it and immediately see the flaws -- and not just experienced jewelers.

The Third C- Color

Colorless diamonds are the most sought-after since they allow the most refraction of light (sparkle). Off white diamonds absorb light, inhibiting brilliance.

When jewelers speak of a diamond's color, they are usually referring to the presence or absence of color in white diamonds. Color is a result of the composition of the diamond, and it never changes over time.

Because a colorless diamond, like a clear window, allows more light to pass through it than a colored diamond, colorless diamonds release more sparkle and fire. The creation process of a diamond ensures that only a few, rare diamonds are truly colorless.

Thus, whiter a diamond’s colors the greater its value.

To grade 'whiteness' or colorlessness, most jewelers refer to GIA's (Gemological Institute Of America) professional color scale that begins with the highest rating of D for colorless, and travels down the alphabet to grade stones with traces of very faint or light yellowish or brownish color. The color scale continues all the way to Z.

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Which Color Grade Should I Choose?

Diamonds graded D through F are naturally the most valuable and desirable because of their rarity. Such diamonds are a treat for the eyes of anyone. But you can still obtain very attractive diamonds that are graded slightly less than colorless. And diamonds graded G through I show virtually no color that is visible to the inexperienced eye.

And while a very, very faint hint of yellow will be evident in diamonds graded J through M, this color can often be minimized by carefully selecting the right jewelry in which to mount your diamond. Keep in mind that, while most people strive to buy the most colorless diamond they can afford, there are many people who actually fancy the warmer glow of lower-color diamonds.

The Fourth C- Carat Weight

A carat is a unit of measurement, it's the unit used to weigh a diamond. One carat is equal to 200 milligrams, or 0.2 grams.

A carat is the unit of weight by which a diamond is measured. Because large diamonds are found less commonly than small diamonds, the price of a diamond rises increasingly to its size. Read on to understand what a carat is and how it affects the appearance of a diamond.

The word 'carat' is taken from the carob seeds that people once used in ancient times to balance scales. So uniform in shape and weight are these little seeds that even today's sophisticated instruments cannot detect more than three one-thousandths of a difference between them.

The process that forms a diamond happens only in very rare circumstances, and normally the natural materials required are found only in small amounts. That means that larger diamonds are uncovered less often than smaller ones. Thus, large diamonds are rare and have a greater value per carat.

Certify The Diamond’s Worth.

It’s necessary to always read the “Fineprint” carefully before signing a document, the same way the certificate is a 'Blueprint' of a diamond; it tells you the diamond's exact measurements and weight, as well as the details of its cut and quality. It specifically points out all the individual distinctiveness of the stone. Certificates also serve as proof of the diamond's identity and value.

A certificate describes the quality of a diamond, but it does not place a monetary value on the gem.

Why Do I Need A Certificate?

You can make a choice while shopping for certified diamonds as it allows one to make a selection and to compare one diamond with a particular weight and quality with other diamonds of similar weight and quality to determine which has a better value.