Why is a boron doped diamond xtal blue ??? hello :) Unfortunately I am not able to find the quantitative description of how a concentration of 1ppm Boron doped in a diamond crystal can produce a blue color such as the http://en.wikipedia.org/wiki/Hope_diamond" [Broken]? The doped boron creates an energy gap of 0.4 eV above the valence band. I will be really thankful for a quantitative description of the process. Thanks in advance.