Colours

Color has three main components: Hue, Tone and Saturation.

Hue is described as the shade, tint or sensation of a color. The GIA GemSet has 31 Hues which can be used to describe viturally all colored gemstones. The complete GIA GemSet has 324 sample hue colors with varying Tones and Saturations.

Tone is described as the relative lightness or darkness of a Hue. The GIA Tone Scale is divided into 11 grades, 0 to 10, with 0 being colorless to 10 being black.

Saturation is described as the strength or purity of a Hue. The GIA Saturation Scale is from 1 to 6. The lower numbers (1, 2 or 3) of warm colors such as red, orange or yellow tend to look brownish and the cool colors such as blue and green tend to look grayish. Level 4 no longer shows either grayishness or brownishness, while neither is strong or weak. Level 5 is strong and level 6 being vivid, almost over colored.

 

GIA Hue, Tone & Saturation Scales

How Color is described using the GIA Color Grades for Colored Gemstones.

Hue

 

 

Tone

 

RP/PR

Red-Purple or Purple-Red   0 C – Colorless/white

stpR

strongly purplish Red   1 EXL – Extremely Light

slpR

slightly purplish Red   2 VL – Very Light

R

Red   3 L- Light

oR

orangy Red   4 ML – Medium Light

RO/OR

Red-Orange or Orange-Red   5 M – Medium

rO

reddish Orange   6 MD – Medium Dark

O

Orange   7 D – Dark

yO

yellowish Orange   8 VD – Very Dark

Y

Yellow   9 EXD – Extremely Dark

gY

greenish Yellow

YG/GY

Yellow-Green or Green-Yellow

styG

strongly yellowish Green

yG

yellowish Green

slyG

slightly yellowish Green

G

Green

vslbG

very slightly bluish Green

bG

bluish Green

vstbG

very strongly bluish Green

GB/BG

Green-Blue or Blue-Green

vstgB

very strongly greenish Blue

gB

greenish Blue

vslgB

very slightly greenish Blue

B

Blue

vB

violetish Blue

bV

bluish Violet

V

Violet

bP

bluish Purple

P

Purple

rP

reddish Purple
 

Saturation

gr(br)

grayish(brownish)

slgr(br)

slightly grayish(brownish)

vslgr(br)

very slightly grayish(brownish)

mst

moderately strong

s

strong

v

vivid
 

Exceptions (Saturation)

pk

pink

brn

brown
 

Color by Spectrum Exceptions (Saturation)

w

white

n

none, colorless or clear

b

black