The 4 C's are four variables that are used to calculate the value of a diamond -- Clarity, Color, Cut, and Carat Weight

Clarity describes the clearness or purity of a diamond. This is determined by the number, size, nature, and location of the internal (inclusions) and external (blemishes) imperfections. To determine a diamond's clarity, it is viewed under 10-power (10x) magnification by a trained eye. Most diamonds contain very small natural birthmarks known as inclusions. The fewer and smaller the inclusions are, the less likely it is that they interfere with the passage of light through the diamond, and a diamond gets its beauty from how it reacts to light. A diamond that is free from both inclusion and surface blemishes is very rare and therefore more valuable.

The clarity scale is broken down into the following grades:

Symbol Meaning Definition F Flawless Free from all inclusions or blemishes. IF Internally Flawless No inclusions visible at 10x magnification. VVS1 Very Very Slightly Included #1 Inclusions that are extremely difficult to locate at 10x. VVS2 Very Very Slightly Included #2 Inclusions that are very difficult to locate at 10x. VS1 Very Slightly Included #1 Minor inclusions that are difficult to locate at 10x. VS2 Very Slightly Included #2 Minor inclusions that are somewhat difficult to locate at 10x. SI1 Slightly Included #1 Noticeable inclusions that are easy to locate at 10x. Sl2 Slightly Included #2 Noticeable inclusion that are very easy to locate at 10x. I1 Included #1 Obvious inclusions. Somewhat easy to locate with the unaided eye. I2 Included #2 Obvious inclusions. Easy to locate with the unaided eye. I3 Included #3 Obvious inclusions. Very easy to locate with the unaided eye.

Color describes the amount of color the diamond contains. This can range from colorless to yellow with slight tints of yellow, gray or brown to the ver rare "fancy" colors such as, pink, blue, green and red. Even though diamonds come in different colors, the most common color is yellow. The rarity of color is where we see the price difference. The general rule of thumb when looking at diamonds is "less color equals greater rarity, therefore, a higher price".

The diamond color chart below is considered the industry standard with D representing the best color grade available. The most popular color range is "Near Colorless". That's because diamonds in this range are more affordable and when mounted can appear just as colorless as diamonds in the "Colorless" range.

The rarity of "fancy" color diamonds is what make the price go up. If you are looking for one of the "fancy" colored diamonds don't except to pay less, in fact the cost is more than a diamond in the D or F range, all things being equal.

Cut refers to the proportions, finish, symmetry, and polish of the diamond. These factors determine the fire and brilliance of a diamond. With the advent of technology, the cut of the diamond can be determined through the use of the Dia-Mension system, a computerized system which takes accurate measurements and proportions of a diamond in seconds, in addition to the standard millimeter gauge.

Diamonds are cut into a number of different shapes;

Most diamonds have one of three basic facet arrangements brilliant, step, or mixed. Brilliant cut diamonds have facet pattern that radiates from the center of the stone toward the edge with triangle or kite shaped facets, ex. Round Brilliant. Step cut diamonds have concentric rows of tapazoidal facets running parallel to the girdle, ex. Emerald cut. A mixed cut diamond combines both brilliant and cut facets and set cut facets; often this style is seen as a diamond with a step cut crown and a brilliant cut pavilion. Mixed cuts are not common.

Whatever the shape, a well-cut diamond is the work of a master diamond cutter. It is the cut that enables a diamond to make the best use of light. Light reflected from on facet to another is then dispersed through the top of the stone. If the cut is too deep, light escapes through the opposite site of the pavilion. If the cut is too shallow, light escapes out the pavilion walls before it can be reflected .

The proportions displayed by the stone are very significant. Two of the key factors in the grading of cut quality -- table percentage and depth percentage -- are usually expressed on grading reports. Measurement of three different parameters allows for easy calculation of these percentages by using the formulas expressed below.

For example, for a round brilliant cut diamond, table percentage is calculated as follows:

Table (%) = longest table measurement (in mm)
average girdle diameter (in mm)

And for depth percentage:

Depth (%) = depth (in mm)
average girdle diameter (in mm)

Without attention to quality cutting, light is lost and not returned to the eye.

Proportions Criteria are as shown below:

	"Premium Cut"	"Tolkowsky Ideal Cut"	"Excellent Ideal Cut"
Total Depth	58.8% - 63.8%	58.0% - 63.8%	59.2% - 62.4%
Table Size	58.0 - 61.0%	53.0% - 58.0%	52.5% - 58.4%
Crown Height	13.0% - 17.0%	14.2% - 16.2%	--------------
Crown Angle	32.7° - 36.3°	33.7° - 35.8°	32.5° - 35.4°
Pavilion Depth	41.7% - 45.0%	42.2% - 43.8%	41.5% - 44.4%

Each cut style above represents, in the opinion of its respective designer, those proportions which best balance the qualities of brilliance and dispersion ("fire") within a round diamond.

Carat is the unit of weight for the diamond and the easiest to understand. Carat weight is simply the weight of a diamond and does not necessarily relate to the size. Diamonds are weighted in carats and one carat is equal to 1/5 of a gram. Diamond weights can also be defined in point or percentages. A carat is further subdivided in 100 points ( 0.01 carat = l point ). One carat is equal to 0.20 grams. Value per carat increases with carat size, because larger rough diamonds occur less frequently. In other words, 2 half-carat diamonds taken together will not cost as much as 1 one-carat diamond, as the one-carat stone is more rare.