Before investing in a diamond, it is essential to understand the factors that determine the value of a diamond. The most important of these factors are known as "The Four Cs of Diamonds":
Carat Weight, Color, Clarity, and Cut.
The carat weight of a diamond is the easiest detail to understand and verify. The "carat" is the unit used to measure the weight of a diamond or gemstone. A weight of 5 carats is equal to exactly one gram. Each 1/100th of a carat is called a "point", so half a carat (0.50 carat) can also be called 50 points. The weight of a diamond can be checked with a certified diamond scale.
Diamonds are given a color grade to determine how colorless they are. The closer a diamond is to being colorless, the higher its value. Diamond color ranges from colorless to different tints of yellow. Color grades are given from a "D" for an absolutely colorless diamond all the way to "Z" for a light yellow diamond.
A diamond's color grade is determined by a gemological institute by comparing it to a set of master stones. An experienced jeweler may also be able to tell you the approximate color of a diamond after examining the stone under pure white light. Other colors and more intense shades of yellow are called fancy-color diamonds.
Since diamonds form under extreme heat and pressure in the earth, it becomes extremely rare to find a gemstone without any natural inclusions on or within the stone. The size, type, location, and number of visible inclusions determine a diamond's clarity grade as shown below:
VVS1-VVS2 Very very slightly included. These diamonds have inclusions that are very difficult for a skilled observer to see under 10x magnification.
VS1-VS2 Very slightly included. Diamonds with VS clarity have inclusions that are not visible with the naked eye but may be observed under 10x magnification with some effort.
SI1-SI2 Slightly included. SI clarity designates diamonds with small inclusions that are easily visible with 10x magnification. Some SI inclusions may be visible with the naked eye. Only the EGL has created a clarity grade of SI3 for diamonds that they regard as having a clarity between SI2 and I1.
I1-I3 Included. The I grade for clarity designates diamonds with small to medium inclusions which are visible with the unaided eye.
Color and clarity are the main factors that determine the material quality of a diamond, but regardless of color and clarity, how well it is cut determines whether or not a diamond looks the best it possibly can.
Cut does not refer to the shape a diamond is cut (round brilliant, pear shape, heart shape, etc.), instead it refers to the quality of the stone's cut. The quality of the cut depends on many factors, including conformance to the correct number of facets, correct proportions, angles, symmetry, girdle thickness, and the final polish among others.
These factors affect the brightness, shine, and overall look a diamond shows when light shines upon it.
The cut quality is the most difficult of the four Cs for a non-professional to determine. Generally, a grade for the overall cut has not been given on certificates by gemological laboratories since it is just not a matter of measurements, but also a matter of overall look. The EGL has given special certificates only for Ideal Cut diamonds. Recently, starting in January 2006, the GIA has started to give cut grades only to round brilliant diamonds, but not for other shapes.
Another factor which also affects a diamond's quality and price is an effect called fluorescence. Some diamonds emit a visible light when seen under ultraviolet light. This effect is usually unnoticeable under regular light. Some prefer to have a diamond with little to no fluorescence, while others do not mind either way. Fluorescence ranges between none to strong. Mozaffarian Online does not carry diamonds with strong fluorescence.