First, let’s understand the structure or body of a diamond :

• 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.

Illustrated in the given below diagram, 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 light is the brilliance that forms the crux of the beauty and sparkle of any diamond.

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.

How do I know which cut of diamond is ideal for me ?

You can choose your ideal cut by referring to the following grades of diamond cuts,

• Ideal 

  – This is the best of all cuts and is applied to only round diamonds. Expensive than the rest it is meant for people who don’t compromise on the finer things in life.

• Premium

   – A tad less expensive than the Ideal cut, the premium cut diamonds allows you to buy a bigger diamond at the same cost offering almost the same brilliance and fire as ideal cut.

• Very Good 

  – Moderately priced amongst all the grades, these diamonds reflect most of the light that enters them, creating a good amount of brilliance. While cutting these diamonds, the cutter opts to stray a little from the ideal diamond proportions to create a larger diamond. The effect is less briiliance than the above two grades of cuts but a larger size.

• Good 

  – Instead of cutting the extra weight off from the original crystal to create a smaller premium quality diamond, the cutter opts to maximize the area of diamond. Excellent choice for people who want to save on the cost of purchasing a diamond without compromising much on the quality.

• Fair & Poor 

  – This grade refers to diamonds which reflect only a small amount of light that enters through them. Ideal for people who are on a shoe string budget and yet want a bigger sized diamond.

Color :

The second important criteria while judging a diamond is its color. Diamonds are graded into categories using alphabets. The color scales runs D, E and F for most expensive white diamonds to categories from M to Z for light yellowish color.

A colorless diamond can be compared to a clear transparent window that reflects back the maximum amount of light. Hence a diamond with the color ‘D’ or alphabets closest to it will display the highest brilliance. The formation process of a diamond ensures that only a few, rare diamonds are truly colorless. Thus, the whiter a diamond's color, the greater its value.

Diamonds graded D through F are extremely rare and that is what makes them most desirable and expensive. Such diamonds are cynosure of all eyes but difficult to obtain. As diamonds graded G through I show virtually no color to the eyes of a lay man and are less expensive, they are most commonly used in jewellery. They too offer a good deal of brilliance and sparkle.

Diamond graded from J through M will have a hint of yellow color and will display lesser brilliance and sparkle.

Also available are Fancy natural colored diamonds such as red, pink, blue, green, yellow, brown etc. The above rules of grading do not apply to them and they are judged on the basis of the intensity of their color and their rarity.

Clarity :

When a diamond is formed, it is possible for minute particles of non-crystallised carbon or non-diamond crystals to be caught within the diamond. These imperfections are called inclusions.

Inclusions are not really visible to the naked eye, however they interfere with the passage of light through the diamond. Therefore the fewer inclusions a diamond has, the more expensive it is and also rare.

A diamond’s clarity refers to two things,

1) Inclusions which are found within the diamond and are included in internal flaws
2) Blemishes which are found on the surface of diamond and are included in surface flaws

However, in the diamond grades used to denote clarity, none of the grades include the term "blemish” and 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).

Process of determining a diamond’s Clarity :

Like color, clarity is also categorized using international grading scales. The categories of clarity are decided by the number, size and position of the inclusions within the diamond. A 10x loupe magnifying glass is used for grading a diamond’s clarity. Grades range from Flawless (diamonds which are completely free of blemishes and inclusions), to Imperfect 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 and also easily detectable by the naked human eye. Buying diamonds in any of these grades is not recommendable.

Carat

A carat is the unit of measure used to determine the weight of a diamond. The term "carat" is derived from the original method of using carob tree seeds to weigh diamonds. One seed from this tree was equivalent to one carat.

The actual weight of one carat is equal to 0.2 grams or 200 miligrams. Further to accurately ascertain the weight of diamonds each carat is divided into 100 points. Diamonds of less than one carat in weight are called as "pointers" or “cents”. For example, a 0.15 carat diamond would be called a "15 pointer".

A diamond is formed in the rarest of rare circumstances, and typically this phenomenon is 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. For that reason, the price of a diamond rises exponentionaly to its size.

Diamonds are usually weighed prior to setting for more accurate measurements. The pricing of diamonds is done according to its caratage, after considering its quality. The carat weight of a diamond is the only ‘C’ which is indicative of its size, and not indicative of a diamond's quality. Two diamonds having the same carat weight, the one of better quality will command a higher price per carat.

Shapes of Diamonds 
After you are aware of the four ‘C’s, you can choose which shape of diamond to go for. The most popular and traditional diamond shape is round brilliant cut diamonds. But there are several other fascinating shapes which also appeal to woman who like to stand out.