What tone levels of the GIA Colored Stone Grading System apply to grading transparent colored stones?

The GIA Colored Stone Grading System utilizes a scale to assess the tone levels of transparent colored stones, which ranges from 2 through 6. This scale is critical in determining the overall visual quality of the stones.

Tone refers to the lightness or darkness of a color, and in this grading system, each number from 2 to 6 reflects a specific tone range that helps categorize the stone's hue. A tone of 2 indicates a very light color, while a tone of 6 indicates a very dark color. This range effectively covers the majority of typical transparent colored stones, allowing gemologists to provide accurate assessments regarding their appearances.

Understanding this scale is essential for anyone involved in the trade or evaluation of colored gemstones, as it aids in communicating the quality and desirability of the stones to clients and colleagues alike. The chosen range provides a structured approach, ensuring consistency and clarity in grading practices within the industry.