Colour in colored diamonds
With this basic background in colour, we can begin a more advanced discussion of colour as it occurs/appears in the face-up direction of any natural coloured diamond, with confidence.
When colour diamonds are concerned the expression of colour is a unique, and quite confusing to most people, because it is the result of purposeful manipulation (i.e. cut and polish) of the diamond to produce an exceedingly complex mosaic of multitude of colours which derive from the natural inherent body colour of the diamond. The typical mosaic we know as what polished diamonds look like is a far-cry light-show display which we consider much more magnificent than the expression of the colour in the rough diamond.
The flat, opaque colour of a paint colour sample chip is distinctly simpler and vastly different from the complex, dynamic expression of colours (i.e., variety of tones of a given hue) which are seen in the face-up direction of a transparent, coloured diamond. While it is called “face-up colour” (singular), what we see when viewing a transparent polished coloured diamond in a “normal” (i.e. overhead) position, with light striking from above is that complex mosaic of reflected and refracted multitude of colours, which we attempt to “sum-up” into a definition that answers the all important question: What is the colour of this diamond?
Common colour name: Verbal terms used to describe the colour of diamonds (and other coloured objects) by providing an analogy with a similar coloured object. Such terms are derived from the names of plants, animals, flowers, birds, pigments, rocks, metals, fruits , trees, foods, jewels, beverages, and various other items that exhibit identifiable colours. One of the most complete lists of common colour names was prepared by Judd and Kelly (Kelly 1955; Judd 1979). Their list organizes more than 7500 frequently used colour names such as apple green, lemon yellow, strawberry red, ink black, etc. Such colour names have gained acceptance through customary usage in the English language as well as in other languages. These names are often used to describe colour in a promotional sense in various industries including art, agriculture, biology, ceramic, chemical, fashion, food, gemstone, horticulture, jewelry, paint, and textile. When used in their proper context, common colour names are quite effective for describing the colour of a diamond and for rapidly communicating colour appearance from one person to another at the promotional (consumer) level. However, if an accurate colour description is required, most colour professionals agree that common colour names represent the least precise method of communicating colour (Kelly 1976). Instead, colour experts prefer to describe the attributes of hue (red, green, blue, etc.), lightness (light, medium, dark, etc.) and saturation (weak, moderate, strong, etc.) in verbal terms or by using numerical colour notations derived from a colorimeter (e.g., L*=45, a*=-4.6, b* =47, C*=47.2). When used correctly, common colour names offer the diamond collector a vast assortment of terms for describing the colour of a diamond. (Eiseman 1990; Evans 1948; Fairbanks 1965; Federman 1990; Hofer 1988 Nos. 2 & 3, 1989 No. 5; Judd 1979; Kelly 1955 & 1976; Kornerup 1963; Kuehni 1983; Maerz 1950; Nickerson 1940; Parsons 1965; Sterns 1968; Zeitner 1963)
Upon examination of the diamond literature published over the past two hundred years, it was found that there exists no single authority for a definitive answer on the subject of colour in diamonds. Coloured diamonds are mentioned by several authors, yet references to various colour descriptions, colour grades, and visual colour sensations are often vague or vary from author to author.
Scattered among the old and new diamond literature, for example, one encounters several traditional colour names such as red, green, yellow, and blue that are used to describe the colour of diamonds, yet there are very few references to other colours such as purple, olive, orange, and gray. Among the same literature, there are also common colour names such as absinthe, coffee, jonquil, salmon, and others, which have been in widespread use for more than a century in the diamond industry. These so-called common colour names began their use at the commercial (promotional) level and eventually were passed down to following generations through customary usage over many years. The general tendency in the diamond industry has been to select common names that refer to material objects which exhibit familiar and identifiable colours. Therefore, common names that refer to abstract items (spoken outside the diamond industry) such as elephant skin, Indian lake, strawberry blonde, etc., are not considered in this particular glossary.
"The purpose of a colour name is to communicate the appearance of a given colour or to enable us to 'think in colour'. Thus the colour name must be so characteristic of the colour's appearance that it is readily understood by others. Since our environment is the source of colours, it is here that we must look for objects of typical colours, objects tor which we already have names and which can be used to designate a characteristic appearance. "
A. Kornerup 1963
In certain cases (e.g., Prussian, hyacinth, teal, etc.), a common colour name has lost its original meaning because of the dulling of memory or the disappearance of the actual colour sample. With many other common colour names (e.g ., flesh, peach, rose, sapphire, sea, wine, etc.), there is confusion regarding the actual hue, lightness, and saturation of the material object. For example, sea green defines a wide range of green colours from bluish to yellowish (Hue), having light to dark lightness (Lit) and weak to moderate saturation (Sat), whereas a colour name such as lime green refers to a more specific colour: a yellowish green (Hue), with medium (Lit) and moderate to strong (Sat). The ability to recognize these distinct colour differences among coloured objects enables a collector to choose the common colour name that is most appropriate for describing a given coloured diamond.
To confirm this random selection of colour names, a person need look no further than the present diamond industry. In the commercial diamond market, the tendency is to generalize (oversimplify) colour descriptions rather than to choose a common colour name that best describes the true appearance of a coloured diamond. The motivating factor for this haphazard selection of common colour names is related to the commercial attitudes and financial concerns of wholesale diamond merchants and retail jewelers. In their efforts to sell coloured diamonds, merchants and jewelers often describe colour with only a limited number of common colour names (e.g ., aqua, bubble-gum, canary, champagne, chartreuse, coffee, cognac, emerald, jonquil, pumpkin, rose, ruby, salmon, sapphire, etc.). These are usually names that connote a "positive illusion" about the colour, which facilitates the sale. Conversely, colour names such as brick, drab, flesh, ink, ochre, steel, straw, etc. , are seldom used by merchants because they supposedly elicit a "negative illusion" of colour, thus endangering a sale.
Diamond collectors on the other hand have discovered that from the 7500-plus common colour names available, there are a limited number of names which, when used in the proper context, can be quite effective for communicating the precise colour (i.e., hue, lightness, and saturation) of a coloured diamond. This enables coloured diamond collectors to use a substantially larger list of common colour names, most of which are familiar to the general public.