Assessing Color and Quality in Yellow Gemstones
Gemologists assess color by considering hue, tone, and saturation. For yellow gemstones, the primary hue should be yellow. The most valuable stones are a pure yellow hue, but secondary hues may be present. For yellow stones, secondary hues are green, orange, and/or brown. Green secondary hues are usually undesirable. However, when slight, they may add a “neon” quality to the stone. Orange secondary hues are generally preferable. For example, popular “golden” colors have slight orange hues. Brownish colors would make ideal choices for an autumnal jewelry project.
Unlike most colors, yellow hues reach their gamut limit at relatively light tones. This means that a bold, highly saturated yellow color will occur with a tone, or darkness, of about 20-30%. Still, very light yellow tones may appear to be off-color white stones.
Because the tone is lighter in yellow gems than in other colored stones, imperfections in the gem are more visible. This means that a higher clarity grade is more important in yellow gems relative to other colored stones. Large or dark inclusions are particularly undesirable, as these have the greatest impact on a gem’s appearance.
If you’re considering a yellow gemstone…