Color defines a gemstone, and unlike diamonds, color is considered the most important of all its defining characteristics. The five factors affecting color are hue, tone, saturation, color distribution, and environment.

Hue

Hue is the precise spectral color of a gem. Specific gemstones are usually found in a range of hues. The primary hue is the main color accompanied by secondary hues. For example, rubies range in hue from slightly purplish-red to slightly orangish-red. At Earth Treasures, we try to stock only those gemstones with desirable hues.

Tone

Tone refers to the depth of color from light to dark. Dark tones in rubies and sapphires are not desirable because the gems lose their transparency and appear inky. Light tones in any gem will give them a washed-out appearance. We strive for medium to medium-dark tones for optimal beauty.

Saturation

This refers to the purity of color which is affected by overtones of brown and gray. Overtones will make a gemstone look less vivid or intense, therefore, strong color saturation is most desirable.

Color Distribution

Evenness of color can drastically affect the beauty of gems. In some stones, color isn't evenly distributed but may exist in zones. This is frequently observed in sapphire, ruby, amethyst, and citrine. When a gemstone is tilted or rotated, streaks of colorless or lighter tones may be observed. Obvious color-zoning is not desirable and should be avoided.

Environment

Colored gemstones are drastically affected by surrounding colors in a room or lighting conditions. Be aware that gems will often appear different under different conditions. Rubies look best in natural daylight or incandescent light bulbs and worst under cool white fluorescent lights. This is due to the lack or increase of some spectrum colors in various light products. For this reason, rubies appear richer in yellow gold and sapphires look better in white gold.