Gemstone guide
Color in Colored Stones
Hue, tone, and saturation—and how they shape the appearance of colored gemstones.
Hue
The color itself
Stones are rarely one pure hue. A sapphire is usually blue with a hint of violet or green, and which way it leans matters to both the look and the price.
Tone
How light or dark it is
Very dark stones read closer to black than to color; very light ones look washed out. The middle of the range is where the value sits.
Saturation
How vivid, versus how gray
This is where most of the price lives. Two stones of the same hue and tone can differ substantially on saturation alone — one vivid, one muted by gray or brown.
A caution
There is no D-Z here
Colored stones have no single universal color grade. Descriptions vary between laboratories and dealers, which is why looking matters more here than reading a grade does.