The Color Codex

An innovative approach for establishing the color of gemstones.

By By Christopher P. Smith, GG, FGA and Çiğdem Lüle,

Figure 1

Color is the most important characteristic of a colored gemstone. The specific hue, saturation and tone all blend to form the overall color impression that one sees when looking at a fashioned gem. However, for consumers, and even many gem trade professionals, trying to understand color as a three-dimensional concept is not always an easy task.
The gemstone and jewelry industry has made many attempts to communicate color in a meaningful manner. None have achieved a broad industry acceptance for the primary reason that they do not represent the color as it appears in faceted gems. In addition, the color terminology that each system suggested has not always coincided with how the industry at large described and saw color.
To resolve this issue, an innovative new tool has recently been developed. The ColorCodexTM color referencing system (figure 1) is a portable, easy-to-use way for industry professionals to identify the color of gemstones. Composed of a series of color cards, each card is designed to capture the nuance of color seen in faceted gems, providing an objective, observer-based means to identify and standardize the color of a gemstone.
Over the past several years, the industry has gone in the direction of using fanciful color terms, such as “Pigeon’s Blood,” “Royal Blue” and a plethora of others to try and accomplish this^1,2. Nonetheless, the specific colors that these terms are attempting to describe are not well defined and as a result there is little consistency in how such terms are used by various segments of the trade, gemologists and labs (figure 2). In some cases, gem professionals assembled sets of “master reference stones” in order to make color comparisons. However, there are a couple of reasons that make the use of this approach ineffective for larger populations in the trade and even between branches of the same brand. First, nature is a fickle producer. Once a specific color in a gemstone/variety is selected, it is very difficult to find others of the exact same color. The second reason is cost. Although some gem varieties and colors may not be very expensive, others can have price tags that make it too costly to acquire a complete set of master reference stones.

YOU MUST HAVE JAVASCRIPT ENABLED TO VIEW THE SLIDESHOW

Introducing the ColorCodex System
In transparent faceted gems, cutting will create bright reflections of color as well as blackened areas of extinction. Printed opaque substrates and computer screens are unable to adequately convey these nuances. In addition, the color appearance of a gem will be seen to oscillate or change as a stone is rotated and tipped. The ColorCodex approach manages to capture these nuances and most resembles how color appears in a gemstone.
Developed expressly for appraisers, jewelers, gemologists and gem dealers, each ColorCodex card is uniquely numbered in order to identify the card and color appearance. Each card displays six variations of appearance for each color, from lighter shades transitioning through richly to deeply colored shades. This easy-to-use tool for industry professionals resembles the appearance of a faceted, colored gem for direct comparisons. With little instruction and practice, the ColorCodex permits accurate and repeatable results to establish a gem’s specific color (figure 3).

How to Use the ColorCodex System
A consistent routine is essential for standardizing how to use any tool for establishing the color of a gem. Lighting and viewing conditions, such as the specific lighting used, distance from the light source and positioning of the gem are important. These are in addition to guidelines for how to look at a gemstone to establish its color appearance (see How to View a Gem, below).
The ColorCodex is an observer-based color comparison system. Users may compare the color cards to loose gemstones, as well as mounted ones (figure 4). Brightened areas of each color window are best observed in comparison to the areas of bright color reflections in a faceted gem to establish which color card is the best match. Then the overall appearance of the gem — which combines the overall impression of brighter and darker reflections of color, as well as the blackened areas of extinction — should be assessed to determine which color window most accurately reflects the overall color appearance of the gem.
The closest match to a particular window is what the observer must determine. Each card and color appearance value is uniquely numbered. The unique numerical value for each color window combines these as reference numbers. For example, the third color window down from the top of a card may indicate: 34 – 09. This number represents that this window identifies a color appearance from card number 34, with a color value of 09 (figure 5).
There exist an unlimited number of color nuances that may be encountered in gems, which cannot be feasibly reproduced. However, the system is further purposely numbered to recognize transitional colors and color appearances. The cards are evenly numbered (e.g., 30, 32, 34, etc.), thus permitting the recognition of a color between two adjacent cards (e.g., 31, 33, 35, etc.). In addition, a numbering between the six color windows of each card (e.g., 03, 05, 07, etc.), also permits the establishing of a color appearance that falls between two windows (e.g., 04, 06, 08, etc.). (See figure 4.)

Concluding Statements
The ColorCodex is an innovative color referencing tool developed by gemologists to improve color communication at all levels of the gem trade. The system design realistically produces colors, with brilliancy, intensity and extinction, making it the most reliable method for referencing the complex color appearance observed in gemstones.
Through the use of the ColorCodex system, appraisers will be able to more effectively establish the color of gems for replacement, and therefore, market valuations. Furthermore, jewelers,manufacturers and suppliers may use the system for the color matching of pairs, suites and so forth, whereas gemological labs and industry organizations now have a better tool and opportunity to standardize color terms.

How to View a Gem to Establish its Color

To best assess the color appearance of a colored stone, the gem should generally be examined in its face-up position, as opposed to grading a diamond, which is conducted face-down to eliminate brilliance. However, when considering the overall color appearance of a colored stone, one must blend the overall impression of hue, color zoning, various intensities of internal reflections, as well as brilliance, extinction and windowing.
Cutting may also dramatically influence color. Well-cut stones will exhibit the best balance of brilliance and extinction, with ideally little to no windowing, whereas poor cutting can negatively affect the appearance of color due to windowing and an asymmetry of brilliance.
Also important is the area of the color-grading environment, which should be neutral. Brightly colored walls, desks or clothing are best avoided. Consistent lighting conditions is another essential element for accurate and repeatable results.
The distance of the lamp/light from the colored gem is also different from that used for diamond color grading. For colored stones, the stone should be held approximately 18 inches to 20 inches ( 50 cm) away from the light source. If a colored stone is held too close to the light source, the color of some stones can be washed out, while the color intensity in overly dark gems can be enhanced, impairing accurate color assessment.
Once the observer positions and views a gemstone under the proper conditions, the ColorCodex cards can be utilized, comparing the stone to each color window to establish the best match and color notation.

Pre-Existing Color Systems

Of the color communication systems in use today, the Munsell Color Order System, based on Albert H. Munsell’s 1905 publication, A Color Notation³, and Pantone Matching System, invented in 1963 by Lawrence Herbert⁴, are arguably two of the most recognized. Each is used across a broad range of industries, such as paints and textiles.

Figure A: The Munsell Color Order System consists of painted chips organized by hue. There are 40 hue pages. Each hue is defined by the terms value and chroma. Value (tone) is represented on the vertical, chroma (saturation) along the horizontal line. Munsell uses an alphanumeric code to represent color in three-dimensional color space with a notation, such as 2.5R 5/14. The system does not use color names.

Figure B: Pantone Matching System colors are expressed in CMYK codes per color swatch in order to be reproduced on printed media and to be displayed in digital media.

Figure C: Specific to the gemstone industry, several systems have been developed in an attempt to better standardize how color is described and quantified in faceted stones. A few have gained some limited acceptance in the industry. One of the more successful of these is the GemDialogueTM, created and developed by Howard Rubin and Gail Brett Levine in early 1983⁵.
The GemDialogue system consists of transparent sheets that display ten zones of saturation for each of 44 hues. The innovation of this system allowed for the sheets to be overlaid, significantly expanding the number and types of colors that could be referenced.
Also in 1983, C.R. “Cap” Beesley, at that time, owner of the American Gemological Laboratories (AGL), developed the ColorScanTM grading system. ColorScan consisted of a series of cards containing colored windows positioned above a reflective background⁶.Each ColorScancard aimed to grade color for specific gemstone variety, such as rubies, sapphires, aquamarine, citrine and others. However, despite positive reviews from its early testers, only a small number of sets were ever created, so it was never widely available.
In the late 1980s, the Gemological Institute of America (GIA) developed the ColorMaster^TM, a device that utilized a light source and three independently colored dials of blue, green and red filters to illuminate a generated image intended to mimic the color of a gemstone⁷. Although the ColorMaster approach was taught for several years, it was replaced by the GIA color grading system by the end of the 1990s. The GIA color grading system presently in use follows a hue-, tone- and saturation-based approach similar to Munsell

Figure D: The Gem SetTM was a system developed in 1989 by Kenneth and Elaine Roberts⁸ and later acquired by the GIA. The Gem Set consisted of a series of colored plastic molds designed to resemble a faceted gemstone. Each piece was named with GIA color codes indicating hue, tone and saturation, then translated into color names, i.e., gB 4/6 meaning vivid medium-light greenish blue. Although still in use, this system is no longer commercially available.

Figure E: More recently, attempts have been made to utilize computer simulations to characterize and standardize color in gems. Of these, the one that has received the most attention and broadest usage is GemE WizardTM. It was developed and released by Menahem Sevdermish in the late 1990s^9,10. The color notations of GemE Wizard are based on the GIA and Munsell grading systems utilizing hue/tone/saturation codes.
GemE Wizard is a computer-based digital color comparison system that is specifically designed to analyze color for gemstones. The user picks the shape, cut and the hue of the stone, then the relevant screen displays the color variations of the selected hue as a square whereby the exact match is to be decided.

Figure F: The World of Color System was designed and devised by Richard Drucker and Thomas Tashey in 2014¹¹. Pages of the World of Color book follow the Munsell color system in layout and terminology, with an additional transparent overlay that provides the integration of the Inter-Society Color Council (ISCC) and the National Bureau of Standards (NBS) color name charts. An accompanying faceted crown is used to create a three-dimensional presentation of the printed color against the gem being examined.

Richbourg C. “What’s In A Name? The use of historical terminology to describe colour.” Jewellery Business, June 2016, pp. 12-18.
Industry News CIBJO Congress: An Overview – Pigeon’s Blood and Royal Blue Colors Special Debate. InColor, Fall 2016, issue 33, pp. 10 and 11.
Munsell, A.H., 1905. A Color Notation. Boston, MA, USA.
https://www.designface.co.uk/content/pantonehistory
Rubin, H., Levine Brett, G.,1997. GemDialogue, Color Toolbox. Cross Reference Listings of Gemstone Color Systems to GemDialogue Colors. GemGialogue 1997. Reno Park, NY, USA.
Patent for ColorScan, US 4534644 A. https://www.google.com/patents/US4534644
GIA Color Stone Grading Course Notes, Describing and Grading Color, 1990, Assignment 6, Page 18-19, The Gemological Institute of America, Santa Monica, CA, USA.
Patent for Gem Set, US 5143212 A. https://www.google.com/patents/US5143212A
www.gemewizard.com
Patent for GemE Wizard, US 8046274B2. https://patents.google.com/patent/US8046274B2/en?q=gemewizard
11- World of Color, Gemworld International, Inc., 2014. Glenview, IL, USA.

www.color-codex.com

Article from the Rapaport Magazine - January 2017. To subscribe click here.