Professional Jeweler Archive: Fancy-Color Diamonds: A Rainbow of Choices

October 2002


Fancy-Color Diamonds: A Rainbow of Choices

Part 1 of this four-part series explains what causes the color in these unique gems

Of all the gems found on earth, nothing surpasses the palette of natural-color diamonds for beauty, distinctiveness and desirability. Known as fancy-color diamonds, they occur in virtually every color and shade of color. Ruby red, baby pink, grass green and sapphire blue diamonds rank among the rarest and most precious of all gems. And today, more and more consumers are becoming aware of these natural wonders and asking to see them at their local jewelry stores.

Fancy-color diamonds possess a distinctive look not found in any other colored gem. Whatever the actual “body” color seen in a fancy-color diamond, it is augmented by the presence of numerous pinpoint flashes of other colors which are the result of diamond’s high dispersion – diamond’s ability to break up each ray of reflected light into an array of spectral colors. For example, a “yellow” diamond may be yellow, but you may also see pinpoint reflections of green, blue, orange and so on. The body color of the diamond, combined with its high dispersion, creates a fiery scintillation not found in any other gemstone. Even brown diamonds, once regarded as “too common” to use in fine jewelry, are very much in vogue today. Their warm neutral colors and fiery dispersion create a special allure, and since they are so much more affordable than other fancy choices, jewelers worldwide are now showcasing diamond jewelry containing brown diamonds in every shade from the palest beige to the deepest, richest brown tones.

But keep in mind that there are also techniques for transforming off-color diamonds into fancy colors, so before buying or selling any fancy-color diamond it is important to determine the origin of color, that is, whether the color is natural or the result of treatment. There is nothing wrong with buying or selling a treated-color diamond as long as you know it is treated and it is priced appropriately, usually at a price that is dramatically less than a comparable natural-color diamond.

What Causes the Color?

Natural color in diamonds usually results from the presence of trace elements, although in some cases it can result from exposure to radiation naturally (as it was forming in the earth) or from damage to the crystal lattice structure. Natural-color yellow diamonds get their color from the presence of nitrogen, for example, and blue diamonds, from boron or hydrogen. In diamonds where color is due to particular trace elements, the presence or absence of those trace elements can be ascertained through sophisticated testing procedures and can provide an important key in determining whether color is natural or artificial.

The situation is different with green diamonds. The color seen in natural-color green diamonds does not result from the presence of trace elements; green diamonds owe their color to exposure to radiation as they were forming in the earth, eons ago. This creates an unusual dilemma for gem testing laboratories because there are also treated-green diamonds that have been created by humankind using modern radiation techniques. Since radiation is the cause of color in both cases, it poses some identification challenges for laboratories. In some cases a natural-color green diamond will contain certain unique identifying characteristics that distinguish it from the treated stone, and in some cases a treated-green diamonds will exhibit characteristics that identify it as treated. But many green diamonds lack conclusive evidence for positive identification. In such cases, a laboratory report will indicate that a positive determination cannot be made with gemological data currently available. This leaves the door open to the possibility that a positive determination might be made at some future time as new data come to light from continued research and technological advances, but there are no guarantees. In any event, if you are seeking a natural green diamond for a customer you must understand that it may be more difficult to find one with laboratory documentation confirming that the color is natural.

Fortunately, gem testing laboratories are usually able to positively confirm origin of color in fancy-color diamonds, and cases where they cannot are the exception rather than the rule. For this reason, and since origin of color has such a significant impact on rarity and cost, I never recommend the purchase or sale of a natural-color diamond without laboratory verification from a respected lab such as the Gemological Institute of America.

Judging Fancy-Color Diamonds

Fancy-color diamonds have always attracted connoisseurs and collectors, but today they are capturing the attention of a much wider audience. Demand – and pricing – are setting new records. But to succeed in selling fancy-color diamonds, you must take time to learn as much as you can about them. You must learn about the availability of particular colors and the sizes and shapes in which they might be available; some colors occur in a wide range of sizes and shapes, while others are rare in even the smallest sizes.

It is also important to take time to understand the 4Cs as they relate to fancy-color diamonds – especially the subtle nuances of color and their impact on value – and to develop an eye for the important differences that affect not only the beauty and desirability of a particular stone, but its cost. And finally, since most natural color diamonds are accompanied by a diamond report, be sure to take time to understand what the information provided on the report is really telling you.

Next month, we’ll begin with the most important factor you must judge: color.

– Antoinette Matlins, P.G.

The information presented here is an excerpt from Diamonds: The Antoinette Matlins Buying Guide and is reprinted with permission of the publisher, Gemstone Press, Woodstock, VT. For more information about the book, call Gemstone Press at (802) 457-4000 or visit

This collection includes natural fancy yellow and brown diamonds as well as treated fancy pink, red, blue and green diamonds. Courtesy of Grafstein Diamond Corp., New York City; (800) 472-3783 or (212) 750-7588.

Photo by Robert Weldon.

Copyright © 2002 by Bond Communications