Fancy colors in nature occur due to the impurities and traces of other minerals in the stone. For instance, blue color is caused by boron and yellow by nitrogen. The same for the lab-created stones: by adding one mineral or another, we can receive different results.
Fancy color diamonds, lab-grown or mined, are graded according to the three attributes of color: hue (color), saturation (intensity) and tone (light/dark). To grade the color, the diamond is judged against the color reference diamond. If there is no reference stone, Munsell color grading system is useful especially when determining the tone, hue and the saturation of the color. In order to do this, the grader moves the diamond from one chip to another to determine the exact grade.
From Fancy Light to Vivid, the most valuable colors are considered to be pink/red, blue, while brown and yellow are the most common. Green diamonds are usually very light in tone and get their color from radiation, while pink diamonds get its color from dislocations of the atoms.
The clarity in case of fancy diamonds is less important, while the price is much higher than the same carat weight of a pristine white stone.
Depending on the cut and size, the color of the stone can be more or less intense. For instance, to keep as much saturation in a fancy color diamond it can be cut using mixed technique.
Black diamonds, on the other hand, are only graded in one scale: fancy black. Moreover, as they are black due to the high amount of impurities, their clarity cannot be distinguished according to the GIA clarity scale and therefore, another type of certificate is issued: Coloured Diamond Identification. With this certification, it can be known if the diamond is black naturally or it has been treated in the laboratory.
All of our diamonds receive no further treatment, meaning that the fancy color is achieved during the growth process.