Gemstone Color

Generally, gemologists separate a discussion of color into three attributes: hue, tone, and saturation. 

 

Hue

The main color of a gemstone.

This is your first impression of the color: Red, Blue, Orange. Then we modify it by saying something like “slightly bluish green” or “strongly yellowish green”.

The GIA breaks colors out into 31 different hues like this:

 

Tone

How dark or light a gemstone is.

Tone is how light or dark a stone is. Some varieties can span the scale, think of Amethyst or Tanzanite, sometimes very light in tone, sometimes very dark.

 

 

 

Others will only have a narrow range, like Peridot, it is always somewhere in the medium light to medium range.

 

 

Saturation

How much color the gemstone has.

How intense is the dominant hue? Is it dull or vivid? Sapphires are a good example of the saturation of a stone. The highest valued museum quality sapphires are a vivid blue, the bluest blue you can imagine. Then sapphires work their way down to strong, moderately strong and so on until the blue becomes increasingly greyish (or brownish in warm colored stones). 

Tanzanite also adopts a similar pattern: