Research Center: The 4 C's of Diamonds

CUT~  A good cut gives a diamond its brilliance. The angles created by the cut are what let the light reflect. Less light reflected back to the eye means less brilliance. Don’t confuse diamond cuts with shape. Shape refers to the general outward appearance of the diamond, not its reflective qualities.

COLOR~ This the presence or absence of color in white diamonds. Color is a result of the composition of the diamond, and it always remains the same. D is a diamond that is colorless. The grading continues on down to Z( although you won't be seeing too many Z's) Colors D thru F are the diamonds that are most desired because of their look and the fact that they are rare. Diamonds rated G thru I have almost no color visible to the naked eye. Diamonds graded J thru M there will be some yellow seen.

Clarity~

F-IF: Flawless or Internally Flawless. Diamonds classified with this clarity have no internal inclusions. Very  rare.

VVS1-VVS2: Very Very Slightly Included. Inclusions are tiny and few in number and are very difficult to detect, even less than 10x magnification.

VS1-VS2: Very Slightly Included. Inclusions are small and are generally invisible to the naked eye and seen only under 10 x magnifications.

SI1-SI2: Slightly Included. Inclusions are usually either a little larger or greater in number than in a VS stone. . These inclusions are fairly easy to find fewer than 10 x magnifications, though they are usually still invisible to the naked eye.

I1-I2-I3: Included. Inclusions are large and/or numerous and may be visible to the naked eye.