Natural color diamonds are unique as they exist in almost every imaginable color, size and price range. Colored diamonds will vary from the faintest shade of pastel pink, blue or yellow to the most deep or vivid shade of brown, green or orange. The value of natural color diamonds is based on the rarity, strength and variation of color within each diamond.
Natural color diamonds can vary in color saturation or strength from very faint to an intense vivid color. Just a slight shift in color strength can make a colored diamond affordable. The strength of color is one of the most important factors in determining the value of a natural colored diamond. The value increases with the intensity of the most prominent color within the diamond.
In an attempt to bring some uniformity to the industry description of natural color diamonds, gem analysis laboratories have developed the fancy colored diamond color scale to classify the strength or intensity of a diamond’s color. Generally speaking, such gradient scales and tools are a reflection of human attempt to categorize the color the eye sees and judge it within three parametric areas: color hue, tone and saturation.
Natural color diamonds are evaluated from the “face up” position, meaning gemologists look directly through the top of the diamond. Experts at both the Gemological Institute of America (GIA) and the International Gemological Institute (IGI) have three parameters by which they describe color for these exquisite stones: hue, tone and saturation.
Color hue refers to the dominant color of the stone, such as pink, yellow, blue. There can also be modifiers or tints, which impart more than one hue to the stone, casting it into a still separate color category. For instance, a purplish-pink diamond indicates a stone with principal pink hue and purplish tints. If no such tints are present, the hue of the stone is said to be a pure primary color.
Color tone refers to how much lightness or darkness a stone appears to retain even when illuminated. The range, obviously, is from light or very light, to dark or very dark.
Color Saturation describes the strength or intensity of the hue or main color. The saturation of light-toned diamonds can vary from a pastel to vivid and intense. Darker diamonds will range from dark to deep in description.
Natural color diamonds are graded by gemological laboratories in very high-tech environments under controlled lighting environments similar to natural daylight. First, diamonds are tested for treatment, synthetic additions or alterations to ensure authenticity. Most laboratories will scan diamonds with a spectroscope to compare readings with their historical data and utilize High-Pressure-High-Temperature (HPHT, the most common process used to enhance the color of diamonds) detection and other proprietary equipment. Gemologists will also use comparison stones and proprietary color chips to compare two diamonds to each other. Though the face-up appearance is ultimately what determines the diamond color, stones are evaluated from other angles as well.
