The Influence of Tone
Tone is the third most important element that impacts color. A tone is produced by mixing a color with grey. In the ColorCodex™ system, the values of hue and saturation are handled on the horizontal and vertical axis respectively, leaving the third important element in color, tone, to be managed through the use of gray overlays. Five levels of tone are represented in five ColorCodex™ overlays, labeled G1 – G5.
Use of Overlays
When referencing a gemstone that displays a tonal element, the first step is to locate the appropriate color in terms of hue and intensity. The color can then be refined through the use of various overlays to impart a grayish or brownish appearance.
For example, the color of a gemstone may match column 34 and level 07 once the G1 overlay is added. The color reference of this stone would then be represented in the ColorCodex™ system as: 34 – 07 + G1.