Tone is how light or dark a gem's color is, from very light to very dark.
In more detail
The most valued blue sapphires are medium to medium-dark in tone. Stones that are too dark or too light are worth less. A ruby that is too light may be called pink sapphire.
Related terms
- Hue: Hue is the basic color of a gem, such as red, blue or green. A second color can modify it, as in purplish red.
- Saturation: Saturation is the strength or purity of a gem's color, from grayish or brownish to vivid.
- Pink sapphire: Pink sapphire is corundum whose color is pink rather than red. Chromium causes both its pink and the red of ruby.
- Sapphire: Sapphire is corundum of any color other than red. The word alone means a blue stone; other colors take a color word, such as yellow sapphire.