Science of Diamonds / Colored Diamonds
Chameleon Diamonds: The Color-Changing Gems You Have to See to Believe
By Dr. Mike Breeding, Updated August 5, 2025
They may look like ordinary colored diamonds at first glance—but there’s much more to the story than initially meets the eye.
Three phases of transformation: This chameleon diamond shifts from vibrant orange-yellow to olive green, showcasing its rare and mesmerizing color-changing ability. (Courtesy of GIA)
To most consumers, diamonds are prized and lauded for their lack of color; the finest and largest colorless diamonds are the epitome of all that is amazing and majestic in nature. When these stones are free of measurable impurities (termed “type IIa”), they achieve the pinnacle of gemstone beauty and rarity. However, as one starts to learn about the science of color in diamonds, it quickly becomes apparent that “pure” and “impurity-free” may not always be the way to go, especially when it comes to chameleon diamonds.
Meet the Expert
- Dr. Mike Breeding is a senior research scientist at GIA with extensive expertise in diamond spectroscopy and defect-related color phenomena.
- He has authored numerous scientific papers on natural diamond growth, treatment detection, and colored diamond identification.
- Dr. Breeding’s research has been instrumental in understanding the unique properties of chameleon diamonds and other rare gem materials.
Intrigued? Read on to uncover the science and mystery behind chameleon diamonds.
Like their reptilian namesakes, these rare diamonds shift colors. (Courtesy of GIA)
What Makes Fancy Color Diamonds So Rare?
It’s worth noting that the rarest of natural diamonds are those with the deepest and brightest hues—think: blue, red, green and orange—a product of extremely uncommon and unique conditions within the Earth that allow for the “perfect” combination of impurities to occur. Representing less than a tenth of a percent of all diamonds, such fancy colored stones are by far the most valuable gems that exist and have sold at auction for as much as $4 million per carat. (In 2015, Sotheby’s sold the 12.03 carat Blue Moon of Josephine, a fancy vivid blue diamond for $48.4 million.)
What Is a Chameleon Diamond?
One group of fancy color diamonds, however, is not always content to exist as a single color. Chameleon diamonds, much like their namesake animals, can temporarily change color in response to their environmental conditions (left). While they don’t usually have especially vibrant hues or blend in with their backgrounds, chameleon diamonds go from a greenish color to a yellow or orange color when gently heated (don’t try this at home) or removed from light for an extended period of time. Upon cooling or light exposure, they revert to their original greenish hues within seconds (right). These unique diamonds occupy a special niche among diamond collectors.
What Defines a True Chameleon Diamond?
While many diamonds may temporarily change color to some extent, chameleon diamonds represent the specific group of stones that tend to have a greenish color component, phosphorescence to shortwave ultraviolet light (meaning they continue to glow after the UV light is off) and the aforementioned temporary color change; to get a “chameleon” comment on a GIA report for a colored diamond, a stone must exhibit all three of those distinctive characteristics. Chameleon diamonds usually have fancy colors ranging from grayish yellow-green to brownish greenish yellow and occur as faceted stones weighing up to about two carats. The largest reported chameleon diamond is the Chopard Chameleon Diamond, weighing in at over 32 carats (below).
The Science Behind Chameleon Diamonds
There are a number of other interesting properties of these color-changing diamonds. All chameleon diamonds are type Ia, meaning that they have nitrogen impurities. Most of them are dominated by aggregated pairs of nitrogen atoms (type IaA) in the atomic structure.
They also have broad absorption bands at ~480 nm and ~750-800 nm in the visible absorption spectrum, which combine to give them a greenish color appearance. The nature of these two absorption bands is not well understood, but the 480 nm band has been linked by some researchers to oxygen atoms in diamond and the 750-800 nm band appears to be related to hydrogen or nickel impurities.
Infrared absorption spectra confirm the presence of hydrogen atoms in these stones and chemical analysis and photoluminescence have documented that most chameleon diamonds also contain measurable amounts of nickel impurities.
Why Do Chameleon Diamonds Change Color?
The chameleon diamond turns lighter and brighter when gently heated or removed from light for long periods of time. (Instagram: @onlynaturaldiamonds)
Why chameleon diamonds change color is actually quite complex and one of the continuing mysteries for diamond scientists. What we do know is that the combination of absorptions that cause greenish color (480 nm and 750-800 nm bands) must change in some way to provide for the yellow color that follows heating or extended removal from light. Some researchers have suggested that under these conditions, the 750-800 nm broadband temporarily reduces in intensity to produce a yellow color. It’s possible that these somewhat conflicting observations may arise from the mixed nature of most chameleon diamonds.
Growth Patterns: A Hodgepodge of Diamond Structure
Under ultraviolet light, these chameleon diamonds reveal complex growth patterns and internal structures that help explain their rare color-changing behavior. (Courtesy of GIA)
Upon closer examination, most chameleon diamonds show evidence of irregular growth and zonation. These differences are best revealed when examining the stone’s fluorescence under very high energy ultraviolet light. Under these conditions, distinct details of a diamond’s internal structure can be seen by patterns in the fluorescence produced by the distribution of different atomic impurities or imperfections.
Chameleon diamonds tend to show some growth regions that fluoresce greenish yellow and others that are inert or fluoresce blue (below). The boundaries between these regions can be regular and oscillatory, or very irregular and jagged, suggesting clear changes in the growth environment of a chameleon diamond. Using carefully oriented spectroscopic analysis, it becomes clear that the greenish yellow fluorescent zones are dominated by 480 nm bands and the inert or blue zones are hydrogen-rich with 750-800 nm bands.
Although the amount of each type of growth zone tends to be different from stone to stone, the heterogeneity is almost always present. The co-occurrence of these two zones and the association of each zone with an important absorption band strongly suggests that the very existence of chameleon diamonds and their fascinating color change is a product of a constantly changing geological growth environment.
The Unique Appeal of Chameleon Diamonds
Chameleon diamonds are revered by many diamond connoisseurs because of their unique abilities and their unrivaled talent to reveal that a special type of beauty can emerge from chaos.
