Color Grading System - GIA Gemologists

Sapphire Ring Co has incorporated the official GIA Sapphire and Ruby color map below. The charts explain the color grading system used by all GIA G.G. gemologists in their color grading of Sapphires & Rubies. The charts illustrate the wide variations in color gradings for Sapphire and Rubies as well as the three main factors which make up Sapphire's color: Hue, Tone & Saturation.

Please feel free to contact us at any time with any questions you may have on Sapphire color grading and how this is used today to give each Sapphire it's final color grade. Understanding these distinctions is important in properly choosing your perfect color in a natural Sapphire or Ruby.

 

           Hue
           Tone
           Saturation

 

GIA Color Grading Scale


Hue Table

The GIA Colored Stone Grading System includes a description system that uses 31 hue names to describe colored gemstones.

 

Name Code Color
very slightly greenish blue vslgB  
Blue B  
violetish blue vB  
bluish violet bV  
Violet V  
violetish purple* vP*  
Purple P  
reddish purple rP  
red-purple or purple-red RP/PR  
strongly purplish red stpR  
slightly purplish red slpR  
Red R  
orangy red oR  
red-orange or orange-red RO/OR  
reddish-orange rO  
Orange O  
yellowish-orange yO  
orangy yellow oY  
Yellow Y  
greenish-yellow gY  
yellow-green or green-yellow YG/GY  
strongly yellowish green styG  
yellowish-green yG  
slightly yellowish green slyG  
Green G  
very slightly bluish-green vslbG  
bluish-green bG  
very strongly bluish vstbG  
green-blue or blue-green GB/BG  
very strongly greenish blue vstgB  

 


Tone

The GIA Tone Scale helps you judge a gem's brightness or darkness. Three key standards to remember are (3) Light, (5) Medium. and (7) Dark.

 

Name Scale Tone
very light 2  
Light 3  
medium light 4  
Medium 5  
medium dark 6  
Dark 7  
very dark 8  

 


Saturation Scale

Use the GIA saturation scale to judge a gem's strength of color. In warm colors, weaker saturation of 1, 2, or 3 appears brownish. In cool colors, the same values look grayish. In both warm and cool colors, gems with saturations of 4, 5, or 6 are almost always more valuable if all other factors are equal.

 

Name Cool Color Scale Warm Color Name
grayish  
1
  brownish
slightly grayish  
2
  slightly brownish
very slightly grayish  
3
  very slightly brownish
moderately strong  
4
  moderately strong
strong  
5
  strong
vivid  
6
  vivid