The 4 Cs

CARAT
A diamond's weight is measured in what is known as a "carat." This small unit of measurement is equal to 0.2 grams, and carat weight is commonly expressed in points or fractions. There are 100 points per 1 carat. For example, 0.33 carats is usually expressed as 33 points, or 1/3 of a carat.

WHAT DOES TOTAL CARAT WEIGHT MEAN?
A diamond’s total carat weight is determined by the minimum weight of all the diamonds in a single piece of jewelry. For instance, if a pair of diamond studded earrings has a total carat weight of 1/2 (0.50) carat, then each earring in this pair would have an individual carat weight of 1/4 (0.25) carat.

The Federal Trade Commission has strict guidelines about the range of carat weight that a fraction can represent. The diamond you purchase may weigh slightly more or less than the fractional weight specified. The chart below shows the satisfactory ranges for carat weights expressed as fractions.

•    1/4 carat total weight may be 0.21 to 0.29 carats
•    1/3 carat total weight may be 0.30 to 0.36 carats
•    1/2 carat total weight may be 0.45 to 0.59 carats
•    3/4 carat total weight may be 0.70 to 0.84 carats
•    1 carat total weight may be 0.95 to 1.10 carats
•    1 1/4 carats total weight may be 1.20 to 1.29 carats
•    1 1/2 carats total weight may be 1.45 to 1.55 carats
•    2 carats total weight may be 1.95 to 2.05 carats

Why is carat weight important?
The carat weight of a diamond is one of the major factors affecting its price (along with cut, clarity and color). Larger diamonds are rarer than small ones, so value increases exponentially for higher carat weights.

How does carat weight affect diamond size?
As a diamond’s carat size increases, both the diameter and the depth of the diamond also increase. A 1 carat diamond approximately 6.5mm in diameter will not look twice as wide as a 1/2 carat diamond that is approximately 5mm in diameter.
 
CUT
Cut is considered the most important characteristic of a diamond. A good cut gives a diamond its brilliance, which is the brightness that seems to come from the very center of a diamond. A poor cut will leave even a diamond with perfect color and clarity looking dull. The angles and finish of any diamond are what determine its ability to handle light and determine its brilliance.

When a diamond is well cut, light enters through the table and travels to the pavilion where the light bounces from one side to the other before reflecting back out through the table. How the light moves within a diamond is dependent on its cut, and the result of a good cut is the brilliant, flashing, and fiery effect that makes a diamond so attractive.

The width and depth determine how light travels within the diamond, and how it exits in the form of brilliance. If a cut is too shallow, the light seeps out the sides causing the diamond to lose brilliance. If it is too deep, the light escapes out the bottom causing the diamond to appear dark and dull.