Color Grading System - GIA Gemologists

Sapphire Ring Cohas 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.

 

NameCodeColor
very slightly greenish bluevslgB 
BlueB 
violetish bluevB 
bluish violetbV 
VioletV 
violetish purple*vP* 
PurpleP 
reddish purplerP 
red-purple or purple-redRP/PR 
strongly purplish redstpR 
slightly purplish redslpR 
RedR 
orangy redoR 
red-orange or orange-redRO/OR 
reddish-orangerO 
OrangeO 
yellowish-orangeyO 
orangy yellowoY 
YellowY 
greenish-yellowgY 
yellow-green or green-yellowYG/GY 
strongly yellowish greenstyG 
yellowish-greenyG 
slightly yellowish greenslyG 
GreenG 
very slightly bluish-greenvslbG 
bluish-greenbG 
very strongly bluishvstbG 
green-blue or blue-greenGB/BG 
very strongly greenish bluevstgB 

 


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.

 

NameScaleTone
very light2 
Light3 
medium light4 
Medium5 
medium dark6 
Dark7 
very dark8 

 


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.

 

NameCool ColorScaleWarm ColorName
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