Along with the weight of the diamond, color, clarity and cut affect the gemstone's worth. Besides how well the diamond was cut, the actual shape it's cut into is another factor determining its value.
Diamonds can range from being colorless to being light yellow in color, and many can even take on a blue or pink hue. Gemologists grade diamonds on a scale according to how much color they have. The more colorless the diamond, the more valuable it is, as this is a rare characteristic. The color of a diamond is sometimes affected by radiation treatment, which also reduces the value of the gem.
Similar to color, clarity is another big factor in determining the worth of the diamond. The clearer the gem, the greater its value. Many diamonds have inclusions or exclusions. Inclusions are internal flaws, and exclusions are external flaws. Diamonds can also display feathers, pinpoints, carbon spots, clouds and needles. Some of these flaws can make the diamond susceptible to cracking, which would affect its value.
The goal in cutting a diamond is to expose its brilliance. The angles and facets of the cut affect how the stone reflects light. Well-cut diamonds reflect the light best. Likewise, jewelers can choose different fancy cut shapes such as emerald, princess, marquise, pear and oval.