The number one driver of colored gemstones value is in fact the color.
Gemstone color has three factors:
- Hue indicates the basic color, gemstones often contain primary and secondary hues, e.g. (1)
- Saturation indicates how intense or “clean” the color is. Desaturated colors are diluted or modified with different grades of grey (cool hues) or brown (warm hues).
- E.g. (b) blue sapphire appears pure and intense – it has high level of saturation.
- E.g. (d) violet spinel appears dull – it has low level of saturation.
- Tone indicates how light or dark a stone is: add black (dark) or add white (light), e.g. (1, 3 and 4)
|a) Blue-Green, medium saturation, dark tone||b) Blue, high saturation, medium tone||c) Blue, medium saturation, light tone||d) Violet, low saturation, dark tone|
Generally preferred color is pure and intense (high saturation) and is of medium tone (no black, no white). Moving towards violet hues tend to increase the value (blue with violet, red with violet) while moving away from violet tends to decrease the value in relative terms (red-orange, blue-green).