Carat weight is only one factor used in valuing diamonds; however, in May of 2014, a 100-carat yellow diamond sold at auction for $16.3 million. Other factors include the cut of the diamond, its clarity and the color of the gem.
The value of a finished diamond is different from the value of a raw 100-carat diamond. When diamonds are finished, they are given a rating by the Gem Institute of America or other governing body. This rating determines the gem's value. A diamond with blemishes or surface distortions, will command a lower price than one with greater clarity. The cut refers to the skill and precision with which the diamond was prepared during finishing as well as the shape of the finished gem.