The 4 C's of Diamond Grading

A diamond grade can be broken down into 4 categories called the 4Cs. They are Cut, Color, Clarity, and Carat. These are the factors that you as a consumer should be aware of in order to make an educated buying decision. 

CUT

The cut of a stone refers to its make, or proportions, rather than its shape. Proper proportions between the stone's table, crown, and pavilion along with strategically placed facets produce the vibrant display of color and light known as "fire" which is highly desirable. 

COLOR

Diamonds are graded on a color scale from D to Z. D being a colorless diamond and Z being yellow or brown. In general, diamonds with grades D, E, and F are considered to be colorless and G through J to be near colorless according to G.I.A . standards.
The less color a diamond has (whiter) the rarer it is and therefore more expensive it will be. Remember that a stone with less color (D) will not necessarily be more beautiful than a yellowed stone (M), just rarer. Beauty is in the eye of the beholder!
Of course this standard only applies to "white diamonds" as opposed to "fancy" colors.

CLARITY

The Clarity grade is the measure of a diamond's inclusions (flaws) or lack thereof.
Several factors can contribute to a diamond having inclusions such as pressure, extreme heat, and cooling while a diamond is being formed or during a volcanic eruption, which brings a diamond up to the earth's surface through a host stone called kimberlite. 

CARAT

Carat is the unit used to measure the weight of a diamond, or any other gemstone for that matter. The word carat is derived from the carob. Before the advent of modern weight scales, carob seeds were used to determine the weight of a stone.