M. Geller Academy
- Home
- /
- M. Geller Academy
- /
- Learn Fancy Color Natural Diamonds
Fancy color diamonds are some of rarest diamonds, and highly coveted for their intensity, brilliance, and hardness compared to other colored gemstones. Diamonds occur in a wide spectrum of colors, but most commonly present in brown, yellow, blue, green, pink, and red, with hues in between. GIA lists 27 possible diamond colors. While naturally occurring, technological advancements pioneered in the 1940s have allowed scientists to enhance white or brownish natural diamonds into fancy colored diamonds. This is done through three main processes, High Pressure High Temperature (HPHT), irradiation, and annealing. Usually a combination of the two or all processes are applied to mimic the naturally occurring phenomena that alters a diamond’s cubic carbon formation.
Naturally occurring fancy color diamonds are the product of extraordinary and unique conditions. The igneous rock that contains diamonds, kimberlite, endures additional heat and pressure, as well as new elements as it makes its way to the earth’s surface.
When diamonds reach the Earth’s crust, they encounter nitrogen rich areas, the most common trace element found in diamonds. This produces a warm, yellowish or brownish appearance in white diamonds, and when abundant, produces what we know as fancy yellow diamonds. Despite its prevalence and the abundance of atomic presentations, only 10% of natural diamonds have the optimal isolated nitrogen atoms responsible for the sought after rich “canary” yellow color. It is also nitrogen, typically 1aB diamonds, along with nickel, that produces the most common fancy color diamond, brown diamonds. Increasing in rarity, blue diamonds are classified as type IIb diamonds, representing only a tenth of a percent of diamonds. Their coloring is caused by trace amounts of boron, which like nitrogen, is introduced into the diamond’s lattice structure as it enters the earth’s crust, usually as an isolated atom.
Fancy color diamonds produced by deformed lattice structures, rather than specific elements, are rarer still. Fancy green, pink, and red diamonds most commonly result from encountering radioactive elements in the earth’s mantle and crust, or by sheer force as kimberlite is thrust to the surface. In both cases, carbon atoms are forced out of their cubic structure, leaving a vacancy (plastic deformation) which affects how light is absorbed and reflected by the diamond. This creates an optical phenomenon producing color. The plastic deformation responsible for pinks and reds can occur without radiation, however, the specific vacancy deformation that produces green diamonds requires radiation. Long exposure to alpha radiation leaves greenish “stains” on diamonds producing green diamonds. Unlike its counterparts, green diamonds are often not evenly colored or deeply saturated, requiring highly skilled cutting and polishing so as to not remove the irradiated portions. As with almost all natural diamonds, these peculiar diamonds will contain trace elements such as nitrogen, nickel, silicon, and hydrogen which can enhance or distort these fancy color anomalies.
With all these factors, GIA and other leading laboratories grade fancy color diamonds on hue, tone, and saturation. This takes the form of light, fancy light, fancy, fancy dark, fancy intense, fancy vivid, and fancy deep. The grade given by a laboratory is the combination of a diamond’s tone (light to dark) and saturation (strength of a color). If a prevalent hue is present, they will attribute a modifier to the grade such as “brownish” or “reddish". While standardized, it is often difficult to fully encapsulate the appearance of a fancy color diamond, and harder still to separate the three factors that make up color in a meaningful way. As such, despite the popularity of certain grades, no one grade is necessarily better than the other. Ultimately, each diamond should be evaluated on its own merit and carefully selected by each individual.