Rarity of Natural Color

Because a diamond's value is intrinsically linked with its color description, grading colored diamonds has become a science with subtle and nuanced requirements for determining color grade based on hue, saturation and tone. The GIA uses a number of color descriptions to categorize and grade natural fancy colored diamonds. A diamond is graded Fancy, when it’s predominant color (hue), tone and saturation on the diamond affects the diamond’s overall color.

Hue

Hue refers to the diamond’s primary color and it ranges from red, pink, blue, purple, green, orange, to yellow, brown and black. The color of the diamond can be described by a combination of two or more colors such as Yellowish-Orange. On a GIA report, the modifier will be listed before the dominant color. I.e. the predominant color of a Yellowish-Orange diamond is Orange.

The GIA uses 8 dominant color hues to grade color:  Red, Orange, Yellow, Green, Blue, Violet, Purple and Pink. Brown and Grey are not considered within the same grading context as the dominant eight; however they can stand alone with a Fancy grade designation. Brown and Grey are also often used to describe the eight as modifying colors.

27 Hues in Grading Natural Fancy Colored Diamonds:

1. Red (Pink)
2. Orangy-Red
3. Reddish-Orange
4. Orange
5. Yellowish-Orange
6. Yellow-Orange
7. Orange-Yellow
8. Orangey-Yellow
9. Yellow
10. Greenish-Yellow
11. Green-Yellow
12. Yellow-Green
13. Yellowish-Green
14. Green
15. Bluish-Green
16. Blue-Green
17. Green-Blue
18. Greenish-Blue
19. Blue
20. Violetish-Blue
21. Bluish-Violet
22. Violet
23. Purple
24. Reddish-Purple
25. Red-Purple
26. Purple-Red
27. Purplish-Red 

Saturation and Tone

Saturation refers to amount of hue in a natural fancy colored diamond and is stated in terms of light, intense or vivid. Tone refers to Lightness or Darkness of the primary color (Hue). In other words, it refers to the amount of light or dark coloration present in the natural fancy colored diamond.

Color Saturation

There are six categories in the GIA scale that equate to color saturation. Natural fancy colored diamonds are graded in the order of ‘increasing intensity’ from Faint to Deep. In most cases, the more intense or deep the color, the rarer and more valuable the diamond will be.

1) FL                       Fancy Light

2) F                         Fancy

3) FI                        Fancy Intense

4) FDRK                 Fancy Dark

5) FD                      Fancy Deep

6) FV                      Fancy Vivid

Cut and Shape

The shape of a diamond refers to the overall outline of the diamond when viewed from the top. Natural fancy colored diamonds are cut to emphasize their color while still exhibiting brilliance and are often cut into non-traditional shapes to do this.