Colored diamonds may belong more in the category of colored gemstones than in a diamond category. The primary reason is because for colored diamonds the 4 – C’s are no longer the holy grail. Pure red is the holy grail.
Sure, one of the 4 C’s stands for color, but the most important characteristics in judging colored diamonds may be:
- Hue – rather than color, since “color” is primarily used in “color grading”. Various natural hues are more rare, while other hues are more desirable. Hues range from red, blue, green, orange, purple, yellow, brown, black
- Saturation – usually confounds diamond folks, but colored gemstone lovers know that “saturation” refers to the amount of hue (or amount of coloration of the primary hue) in a gem. Saturation is normally stated in terms of weak, fair , medium, strong or vivid
- Tone – is the amount of undesirable (gray and brown) coloration present in the diamond. Tone is often represented as very light, light, medium, dark or very dark.
Note: Not all secondary hues are undesirable. Many undertones add a unique character to a gemstone.
Note 2: Since the diamond crystal is cubic and monochromatic (single refractive), a secondary hue will not appear quite the same as in a double refractive crystal such as corundum (ruby and sapphire)
For purposes of this discussion; high saturation colored diamonds are referenced; while artificially treated, irradiated, or laboratory created diamonds are not addressed.