CARAT WEIGHT
Diamonds are sold by Carat weights.

Carat is actually a measurement of weight, not size. However, it should be relative to size. One carat is divided into 100 points. The most important dimensions of a fashioned diamond are its depth and diameters. These measurements vary slightly even between stones of the exactly same weight they are key identifying characteristics and are used to estimate mounted weight.

It is very common for people to have magic sizes in their minds like- quarter carat, Half carat, carat etc. However people do not realize that there is a very small difference in appearance between, say, 1.34 carats and 1.25 carats or 1.50 carats but certainly a distinct increase in price as the carat weight increases. In the mining process it is very rare to find a large Diamond. This rarity makes them more expensive.
Determining the Carat Weight that's Right for Her
Determining the carat weight that is right for her is a simple choice. Consider the size of her fingers. If she has a fairly small ring size, a smaller diamond will look proportionate on her hand. Find a moderate balance between the color and clarity grades to see how much carat weight you can get for your budget. Also, bear in mind the width of your engagement setting. Find a carat weight that complements the setting nicely without overpowering it, and vice versa.

CUT
The Cut is the most important C of the 4 CS. The Cut actually refers to the quality of the proportions and the shape of the Diamond. Cut, more than any other quality aspect gives the diamond its sparkle. A diamond gets its brilliance and scintillation by cutting and polishing the diamond facets to allow the maximum amount of light that enters through its top to be reflected and dispersed back, also through its top.


When the facet angles are perfect, the light that enters is dispersed back through the diamonds top facets. When a stone is cut too shallow or too deep, that light that enters through the top is allowed to escape through the bottom and does not allow the maximum beauty of the diamond to be realized. The price of these diamonds is significantly cheaper than a well proportioned diamond. Remember, just because two diamonds have the same weight, does not mean they are the same size.

COLOR
Diamonds come naturally in almost every color of the rainbow; however most people are concerned with diamonds in the white range. Along with cut, this "C" is also very important in determining the overall beauty of the diamond. Color starts with the letter D, being the whitest, or best, and goes down the letter Z, being more yellowish. It is the lack of color, or whiteness in a diamond that allows the light to pass effortlessly through the stone and disperse that beauty back to the observer. Color is not so much white versus yellow, as the chart tends to indicate, it is lighter versus dark. A white diamond will look very clean, crisp, and brilliant. A yellow diamond will not really look yellow, as it will look darker and dirty, without nearly the same brilliance. These are differences that you can clearly see, as you do not need to be a gemologist to see these differences.



CLAIRTY
Clarity refers to how many flaws, or inclusions, are in the diamond. In most cases, clarity has very little to do with the beauty of the diamonds, rather it effects how the diamond looks under the microscope. To determine a diamonds clarity grade, it must be examined loose, under 10x magnification by a gemologist. Whatever minute inclusions there may be make every diamond unique. These are nature's fingerprints and in most cases do not mar the diamond's beauty nor endanger in durability. Without high magnification, these flaws are invisible. However, the fewer inclusions, the rarer your diamond will be.

Generally, if a diamond is SI-1 or above, it is flawless to the naked eye). If there is even a tiny inclusion visible to the unaided eye, the stone is usually graded an SI-2 or I-1