Carats

• 
  
  Carats, which are often confused with the gold purity measurement of a karat, refer to the weight of a diamond. A carat is divided into 100 points, and the system is very precise, measuring to the hundredth. For example, a diamond with 80 points would have .80 carats. Of course, the higher the number of points, the more expensive the stone will be.
  
  

Color

• Contrary to popular belief, the price of a diamond increases as the color within the stone decreases. A colorless gem is most desirable, however it is quite difficult for the average person to notice a difference. Color is graded on a scale from D to Z.
  
  Diamonds graded D, E, F are colorless.
  Diamonds graded G, H, I, J are near colorless.
  Diamonds graded K, L, M have a faint tint of yellow.
  Diamonds graded N through Z have a tint of light to dark yellow.
  
  

Clarity

• Slightly Included diamond
  
  Clarity ranges on a scale from flawless to imperfect, and refers to the natural blemishes or "birthmarks" found within the diamond. Most diamonds contain these marks, and it is very rare to find a completely flawless stone, making it very expensive. Gem appraisers use 10x magnification to determine where the diamond lies on the GIA grading scale.
  
  FL: Flawless, there are no imperfections seen under intense magnification.
  IF: Internally Flawless, there are very minuscule imperfections or "blemishes."
  VVS1 and VVS2: Very, Very Slightly Included, under intense magnification; marks exist but are very difficult to see.
  VS1 and VS2: Very Slightly Included; the stone's natural birthmarks are minor.
  SI1 and SI2: Slightly Included; blemishes are visible under intense magnification.
  Included: Marks are obvious under intense magnification.
  
  

Cut

• Diamond facets
  
  This is one of the most important aspects of a diamond, as it is the shape and structure that makes up the appearance. A facet is the angles found within the diamond, as you can see in the photo. The most popular cuts of diamonds are:
  
  1. Round: A 360-degree symmetrical stone with facets pointing toward the bottom. This allows it to reflect the most light.
  
  2. Cushion: A rectangular cut with rounded corners, resembling a pillow.
  
  3. Emerald: A rectangular cut with cropped corners and horizontal facets. Horizontal facets are also known as step cuts.
  
  4. Oval: An elongated version of the round cut, with a length-to-width ratio of 1.5:1.
  
  5. Princess: Square shaped with sharp, pointed corners.
  
  

Colored Diamonds

• Red diamond
  
  Most diamonds are clear; it is very rare to find a colored stone. While the four C's still apply, there is a different color grading scale for the .0001 percent of diamonds that have beautiful colors. While clear diamonds are rated from D to Z, colored diamonds go from Fancy Vivid to Faint. The scale is as follows:
  
  Fancy Vivid (equivalent to D)
  Fancy Deep
  Fancy Intense
  Fancy
  Fancy Light
  Fancy Very Light
  Faint (equivalent to Z)