Consider the infinite number of colors in nature, and how many ways we use color to interpret the world we live in. We associate them with love, passion, anger, other emotions and energy levels, and they permeate our language and for some, our very identities. If you are considering a colored gemstone for an engagement ring, it stands to reason that color is considered the most important quality factor. The more color a stone has the more valuable it is. Mid-tone gemstones are considered the best.
Gem color is divided into 3 factors that are internationally recognized, and they are hue, tone, and saturation:
Hue refers to the spectral colors that you see. Put simply, this is what we mean when we are asked to choose a favorite color. A hue can be pure, such as a perfect blue diamond, or have other shades mixed in to produce hybrid hues, such as a red-orange Madeira citrine. The best gemstones are those with a pure hue; a modifying or secondary color would usually lower the quality of a gemstone. Hue does not refer to the lightness or darkness of a color.
Tone is how we describe the lightness or darkness of a color, as if we added white or black. Each hue can have a lighter version or a darker version and we measure these levels in percentages. When it comes to tone, mid-tones are considered the best. When the tone is low, it gives the stone a milky color and when the tone is too high, it gives a color that is too dark for most people.
Saturation is the amount of color. This is also measured in percentages. Interestingly, with saturation, like tone, more isn’t necessarily better. A saturation of 90% might be less appealing than 85% in many colored gemstones. We use the term ‘fancy’ to refer to saturation of a gemstone, meaning it has the maximum amount of color possible. Some gemstones are said to be ‘color zoned’. If this is the case, it means that it shows different colors in its different body parts, such as mixed tourmaline like watermelon tourmaline. You will not see this in the more expensive varieties.
How Hue, Tone and Saturation Work Together
