Every gemstone has its own color, and thus simply saying a stone is “blue” or “green” does not give a precise enough description. Generally, gemologists separate a discussion of color into three attributes: hue, tone, and saturation. Hue is the primary color, tone is the lightness/darkness of that color in the stone, and saturation is the intensity of that color. The Gemological Institute of America recognizes 31 hues, 11 tones, and 6 levels of saturation. The categories for each of these color components as determined by the GIA is detailed below, and can help you understand the complexity involved with assessing a gemstone’s color.
But what the charts cannot show is what colors of gemstones most appeal to you, and what colors are considered most valuable in the marketplace. You need to consider your own tastes, and your own preferences, when purchasing gemstones. You can contact us to get more information on the color of any individual colored gemstone jewelry piece on our website, and you also know that when buying any product from Diamond Select, you have a 60-Day Worry Free Return if the gemstone color does not meet your expectations when it arrives.
(We note that clear, medium-tone, and highly saturated primary colors are the most preferred and valued gemstone colors. Muted colors and colors between hues, which you might find very attractive and even preferable, thus offer wonderful options that can be less expensive.)
“Hue” is the color of the stone; the GIA color-grading system uses 31 different hues to describe the primary key color of a gemstone. The hue is the first impression of color, which is then modified by tone and saturation, further described below.
These are the 31 different hues recognized by GIA in its Color Stone Grading System, and there are gemstones that fall into each category.
Tone is the lightness or darkness in a gemstone. Think of it like mixing paints; for tones between 2 and 5, it is as if some white is mixed in with the pure hue, and for tones between 5 and 8, it is as if some black has been mixed with that pure hue. So the base color becomes lighter or darker in tone.
There are 11 degrees of tone in the GIA color grading system, but only 7 of them are actually used (2 through 8).
|Tone 2||very light|
|Tone 4||medium light|
|Tone 6||medium dark|
|Tone 8||very dark|
Thus, for example, the tone scale for a Blue hue would be as follow:
Finally, saturation is the brightness or intensity of a hue. The purer the hue, the higher grade it will get on the saturation scale.
The saturation scale goes from 1 to 6. Lower grades (1 to 3) can have a gray or brown modifier. Cool colors, like green and blue, have a gray modifier in low saturation. The warm colors (red, orange and yellow) have a brown modifier.
Any stone that doesn't have a gray or brown modifier will at least be a 4 on the scale.
|Saturation 1||grayish (cool colors) / brownish (warm colors)|
|Saturation 2||slightly grayish (cool colors) / slightly brownish (warm colors)|
|Saturation 3||very slightly grayish (cool) / very slightly brownish (warm)|
|Saturation 4||moderately strong|