The most familiar usage of diamonds today is as gemstones used for adornment a usage which dates back into antiquity. The dispersion of white light into spectral colors, is the primary gemological characteristic of gem diamonds. In the twentieth century, experts in the field of gemology have developed methods of grading diamonds and other gemstones based on the characteristics most important to their value as a gem. Four characteristics, known informally as the four Cs, are now commonly used as the basic descriptors of diamonds: these are carat, cut, color, and clarity.

CUT
There are two aspects referred to when discussing the cut of a diamond. The first refers to the quality of the cut - affecting the brilliance of the diamond - the other refers to the actual shape of the diamond.
Diamonds are available in many shapes. Some of the more common are; round, oval, pear (teardrop shaped), heart, princess (square shaped), Emerald (rectangular shaped), marquise (football shaped) and round.
Of all the shapes available, round diamonds are the shape most capable of being cut to exude the greatest brilliance. The brilliance is determined by the ability of the diamond to reflect light. A quality cut diamond will have facets angled to reflect the greatest amount of light.

CLARITY
Diamonds from natural sources are subject to individual flaws including trace minerals and scratches. A diamond without such characteristics is called flawless and is the rarest kind. While these flaws are often not visible to the naked eye, they affect the light reflecting qualities of the diamond which affects the overall brilliance.
Diamond clarity is classified as follows: Flawless, IF, VVS1, VVS2, VS1, VS2, SI1, SI2, SI3, I1, I2 and I3.

CARAT
Carat is the measurement of the weight of a diamond. One carat may also be referred to as ‘100 points’. This means that a half carat would be listed as ‘50 points’ and so on.
The larger a diamond is the more costly it becomes. Since the larger diamonds are much rarer the cost will go up significantly with each increase in size. A one carat diamond will be more than just double the cost of a half carat, however, a ring with multiple diamonds that have a combined weight of one carat will be cheaper than a single stone of that weight.

COLOR
The color of a diamond is rated on an alphabetical scale from D to Z. A typical ‘white’ diamond should be as colorless as possible - a rating of ‘D’ being the rarest and most desirable. When choosing a colorless diamond it is best to stay within the D-J range or the diamond will have a yellow cast which lessens the value. The less natural color the diamond has the more colors will appear in the flashes reflected in the prism.
‘Fancy’ diamonds (diamonds with a rating over Z) come in a variety of shades and include some famous diamonds such as the Blue Hope diamond.
When purchasing a diamond it is important to remember that each of the 4 Cs are of equal importance in an appraiser’s eyes. If budget is an issue, however, you should consider which features are of greatest importance to you and with a little knowledge select the diamond that will hold the greatest value and sentiment for your budget.