Language of Color: Tone
Tone is a color's lightness or darkness. You can get an idea of what tone means in color if you consider that many pinks are light tones of red. The GIA Color Grading System divides tone variations into I I levels, starting at 0, colorless (or white, when graders talk about translucent or opaque stones), and ending at 10, black. For transparent gems, you normally deal with only levels 2 through 8.
Each tone level has a number and a corresponding word term. The Gem Set Tone Samples picture show the tone levels (white, grays, and black) and lists their numbers and corresponding terms.