For fancy-colored diamonds, color far surpasses the other “Cs” (clarity, cut, and carat weight) when establishing value. Therefore, it is critical to understand color appearances and how they affect color grades and descriptions. While everyone thinks they understand color, for most it is an intuitive response rather than a true knowledge of the ordering of color appearances.
Color is described using three attributes:
· Hue (the aspect that permits an object to be classified as red, green, blue, violet, or anything in between)
· Tone (the relative lightness or darkness)
· Saturation (the relative strength or weakness)
The color appearance of a gem is the result of a combination of these three attributes. The Gemological Institute of America (GIA) system for color grading colored diamonds uses 27 hues, which are indicated on the hue circle chart. Some of these 27 hue names include modifiers, such as purplish pink.
A modifier in a hue name (such as yellowish green or orangy yellow) does not mean a lack of purity in the color