Diamonds are graded and categorized through its different characteristics in the diamond industry. Any diamond is graded on the basis of 4C'S.
The 4C'S consist of:
These are the basic details Gemologists and jewelers see in diamonds :
Diamond cut is the most important criteria of grading. Brilliance of a diamond depends on how good the cut is. Furthermore cut is defined and categorized in different grades to help the customers in determining the cut of a particular diamond. The grades are :
Excellent : 'Excellent' cut diamonds reflects the maximum amount of brilliance and fire. It reflects nearly all light that enters the diamond, creating exceptional sparkle and life.
Very Good : 'Very Good' cut diamond properly reflects most of the light that enters the diamond, producing superior fire and brilliance. Under normal lighting conditions, appears very similar to excellent cut, but for a lower price.
Good : Reflects a majority of the light that enters the diamond, for an above average appearance. An excellent value compared to higher cut grades.
Fair/Poor: Allows much of the light entering the diamond to escape from the sides or bottom, reducing perceived fire and brilliance. More acceptable in diamonds weighing less than 0.75 carats, where differences in sparkle are more difficult to perceive. The diamond may appear noticeably dull and lifeless, even to an untrained eye.
The clarity of the diamond is rated by the quantity and position of 'inclusions' or flaws, which bothers the light that passes through the diamond. The rating of the diamond is done in the following categories :
Flawless (without inclusions or imperfections)
Very, Very Slightly Included (VVS1 and VVS2)
Very Slightly Included (VS1 and VS2)
Slightly Included (SI1 and SI2)
Included (I1, I2, and I3) (with inclusions or imperfect)
When most industry experts discuss the color of diamonds, they are generally referring to lack of transparency or color of the diamond. Diamonds are made of 100% pure carbon without impurities therefore they are completely colorless. However, almost all diamonds contain some extent of color impurity caused by traces of nitrogen, boron, hydrogen or other elements. Most diamonds suffer only traces of nitrogen, which produces a pale yellow or brownish color.
To grade color of the diamonds, they should be free, because if the diamond is in the metal, the metal will affect the color we perceive. For example, a slightly yellow diamond might glitter more if categorized under yellow gold while it looks less yellow if categorized under white gold or platinum.
Diamonds are placed table-down, pavilion up, and magnified under 10X loup.
Lettering system from D to Z is used to determine the amount of color in each diamond with D awarded only to rarely complete colorless diamonds.
Grades of Diamond color: Colorless diamonds and diamonds that are yellow or yellowish brown are grouped into the following categories. These varieties do not apply to fancy colored diamonds - they have their own grades.
D-E-F : Colorless
G-H-I-J : Almost colorless.
K-L-M :Pale in color, usually yellow.
It's easier to understand this C of all "4Cs". A unit of weight for diamonds and other gemstones is carat. Weight of a diamond is directly related to the size, and although incorrect, these terms are sometimes used interchangeably. It is a term that is derived from the use of an ancient 'Carob' seed in measuring small weights. Table of common weight-related terms are given below.
One Carat is 0.200 grams (There are 5 carats in 1 gram and 142 carats to 1 oz.)
A carat is divided into 100 parts each called a point. So 1 carat = 100 points.
Three Quarter Carat = 75 points
Half Carat = 50 points
Quarter Carat = 25 points
Scientists have started recognizing the different types of diamonds since 1930. They have grouped diamonds into two categories which are Type I and Type II based on the transparency ratio under ultraviolet radiation. The CVD diamond has been classified into two types; Type I and II diamonds.