In the above photograph we see two natural fancy color diamonds, each stone was graded as Fancy Intense purplish pink, by a major diamond grading laboratory.

While each stone is correctly graded, there are obvious differences between their face-up colors. For example, the stone on the left contains a small amount of purple, is darker and more saturated than the stone on the right. Conversely, the stone on the right has an obvious purple modifier, is lighter and less saturated than the stone on the left.

These color differences between two stones with the same color grade, indicate to the interested collector that each color grade defines a range of color. Thus, with the aid of a color measuring instrument, one can determine if a colored diamond is within a particular color grade range, and determine other important aspects of the color.

Once the face-up color has been visually and instrumentally interpreted, then the collector can use this advanced color data to decide if a particular stone fits into the collection, or satisfies the requirements as an investment.

Example of A Colored Diamond Collectors Authenticated Gemstone Color Analysis & Report (PDF file)