The Orange Color:
Fancy orange diamonds are usually Type Ib diamonds that consist of atoms of nitrogen uniformly distributed in the crystal lattice and absorb blue and yellow light, resulting in an orange color. Because the odds of an orange diamond being only orange are extremely long, they are typically found with modifying colors. The saturation of a color diamond is determined by its intensity. Differences in color appearance are therefore credited to tone, which is the particular point that a diamond falls in the light to dark spectrum.
Secondary Color Modifiers:
A color diamond is generally rare when it exists as one color without any additional modifying colors. The only instance that color in natural fancy orange diamonds can experience even greater rarity and value than if such diamonds were to have just its primary color of orange is when the primary orange color is combined with equally, if not more, rare colors such as red or pink. A “fancy reddish orange” of considerable saturation will therefore be a lot more rare and valuable than a color diamond that has only orange in a comparable saturation.
Tone:
Tone refers to the lightness or darkness of an orange diamond, and the continuum in between. GIA grading does not make a distinction in tones, but to the eye a stone with darker tones may appear more intense in color. For someone looking for the appearance of a Fancy Intense Orange without the price tag of one, a good option may be a Fancy Orange with a darker tone.