Gemstone color grade system

Gemstone color grading system for the Web

Color description
(GIA notation): very light
light;
strong
light;
vs greyish
/brownish m light;
strong m light;
vs greyish
/brownish m light;
sl greyish
/brownish medium;
strong medium;
vs greyish
/brownish medium;
sl greyish
/brownish med dark;
strong med dark;
vs greyish
/brownish dark

Red

orangey Red
n/a

n/a

n/a

n/a

n/a

n/a

reddish Orange

Orange
n/a

n/a

n/a

n/a

n/a

n/a

orangey Yellow
n/a

n/a

n/a

n/a

n/a

n/a

Yellow

greenish Yellow
n/a

n/a

n/a

n/a

n/a

n/a

yellowish Green

slightly yellowish Green
n/a

n/a

n/a

n/a

n/a

n/a

Green

very slightly bluish Green

bluish Green
n/a

n/a

n/a

n/a

n/a

n/a

very strongly bluish Green

Green-Blue or Blue-Green
n/a

n/a

n/a

n/a

n/a

n/a

very strongly greenish Blue

very slightly greenish Blue
n/a

n/a

n/a

n/a

n/a

n/a

Blue

violetish Blue
n/a

n/a

n/a

n/a

n/a

n/a

bluish Violet

Violet
n/a

n/a

n/a

n/a

n/a

n/a

bluish Purple
n/a

n/a

n/a

n/a

n/a

n/a

Purple

reddish Purple
n/a

n/a

n/a

n/a

n/a

n/a

strongly purplish Red

slightly purplish Red
n/a

n/a

n/a

n/a

n/a

n/a

Grey
n/a

n/a

n/a

n/a

Placing the cursor over the top right corner of the pattern displays the color ID, description and web RGB code.

Comments

Gemval color grading system is a simplified modification of the Gemological Institute of America (GIA) color grading standards for natural gemstones. This simplified model is aimed primarily at online gemstone traders, auction dealers and gem collectors. The difference and the most important features of Gemval color grading system are:

- Unlike GIA's standard color set, Gemval web color communication system is designed to fit a 32-bit LCD computer monitor precisely and specifically to enable color recognition via a web interface. For your convenience each pattern refers both to the GIA color scale and to the web color code (RGB code).

- The most interesting and unique feature of the system is a "minimal value gap" modelling. This means we have kept the highest level of detail in color areas, which have the greatest impact on a gem's value, and we have reduced the color precision scale for areas of unsaturated / dark colors, usually applicable to inexpensive gemstone varieties. Therefore the system assures minimal value estimation error.

- The color grade system represents the core of Gemval online appraisal system. It consists of 230 color patterns, 25 base hue sets + grey scale, extended by 6 tones (very light, light, medium light, medium, medium dark, dark) and by 3 saturation grades (strong, very slightly greyish/brownish, slightly greyish/brownish).

Standard gemstone values

Historical values and trends