Cut

• The cut of the diamond refers to the way that the diamond reflects light. Essentially, the better the light reflects off of the diamond, the better the quality of cut. The quality of the cut is measured in two different ways. It can be graded on a number scale from one to eight, with one being the highest quality, or it can be graded by categories ranging from excellent, good, average, commercial and irregular.
  
  

Clarity

• Most diamonds have imperfections in the form of nicks, cracks and fractures, which are called inclusions. Inclusions are found by jewelers through magnification and can have a wide ranking. The ranking in order of best quality to lowest quality is as follows: FL (flawless), IF (internally flawless), VVS1, VVS2 (very very slightly included), VS1, VS2 (very slightly included), Sl1, Sl2, Sl3 (slightly included), I1, I2, and I3 (included). Diamonds in the I category have inclusions that can be seen with the naked eye.
  
  

Carat

• Diamond weight is measured through carats. Carats are measured using a points system, with one carat consisting of 100 points. For example, if a diamond has 60 points it is 0.60 carats. The carat amount of a diamond does not always indicate size. Diamonds that are small can have a larger carat worth than larger diamonds if they are denser. For the most part, the more carats a diamond has, the costlier it is.
  
  

Color

• With a few exceptions, high quality diamonds should be as colorless as possible. Diamonds can be ranked as D (absolutely colorless), J (slight color) or Z (slight yellow). There are also some diamonds that are naturally colored and are also considered to be of high quality. These diamonds can come in shades of yellow, green, blue, pink, orange or red. The red diamonds the most rare of the colored diamonds available and are very costly.
  
  

Certification

• Certification is now available to individuals who wish to verify the authenticity of their diamonds. Labs will rate the diamonds for their cut, clarity, carat, color and dimensions. The process of certification usually takes two to four weeks. The costs of certification, as of 2011, typically start at $75 for one carat and raise incrementally for every carat to be tested afterwards. A report of the diamond's features will be sent back to you through mail.