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.com's color grading system is a simplified modification of the Gemological Institute of America (GIA) color grading standards for natural gemstones. The difference and the most important features of Gemval.com color grading system are:

- Unlike GIA's standard color set, Gemval.com's 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).

- A gemstone's color is probably the most important factor in the online appraisal procedure. To allow selecting a color more straightforward, we have reduced the number of color patterns within the hue and saturation scales. This simplified model is aimed primarily at auction dealers and gem collectors; the system is also suitable for jewelry professionals who trade online.

- The most interesting and unique feature of the system is "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 that the value estimation error remains minimal for neighboring cells of the matrix.

- The color grade system represents the core of Gemval.com's 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).

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