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Standout Chameleon Diamonds


Volume 2, No. 4


Source: Robb Report, Jill Newman

In the late 1950s, an expert at the Gemological Institute of America (GIA) – the world’s leading nonprofit institute devoted to gemological research and education – graded an unusual green diamond. After conducting a thorough examination of the stone, he carefully placed it in the laboratory’s safe and left for the day. When his colleague arrived at the laboratory the following morning to make his own assessment of the treasure, he discovered that the green diamond was gone and that someone had deposited a yellow specimen in its place.

A frenzied search ensued as the technician scoured the lab in search of the missing gem. Sometime later, his panicked hunt came to a startling end when, upon returning, he found the green diamond precisely where had left the yellow one. That was when it occurred to him that the two stones might be one and the same. Scrupulous inspection of the gem in varying levels of light revealed that his hunch was correct. He had in his possession an entirely new category of diamond.

Since that day, the mysterious chameleon diamond has astounded and bewitched even the world’s most eminent gemologists with its shifts in color, from green in bright light to yellow in darkness or at high temperatures. Named for the lizard that changes its hue to camouflage itself, the chameleon diamond is extremely rare, and typically it is found in small sizes of two carats or less, according to Tom Moses, senior vice president of laboratory and research at the GIA. These facts about the astonishing stones make even more incredible Chopard’s recent unveiling of a nearly flawless, 31.31-carat, strawberry-size chameleon diamond – the largest known specimen of its kind. “I was flabbergasted when I laid eyes on the stone,” says Caroline Gruosi-Scheufele, co-president and design director of Chopard, which has not divulged the circumstances surrounding the diamond’s acquisition.

Exactly how the diamond changes color is equally perplexing: Although experts have linked the phenomenon to the stone’s high concentrations of hydrogen, nitrogen, and nickel, the process has not yet been fully explained. While the stone’s chemistry remains unclear, the design possibilities inherent in the gem’s changeable color were immediately apparent to Gruosi-Scheufele, who set the $10 million diamond in a simple ring surrounded by tiny yellow diamonds.

Few among the curious will have the opportunity to view this wonder first hand, it is not showcased in one of Chopard’s international boutiques; Gruosi-Scheufele privately presents the piece to VIP clients who have a deep appreciation of rare stones. “It is for the connoisseur who already owns other important jewels,” observes the GIA’s Moses. He likens the purchase of a chameleon to buying a peculiar classic car. “A car collector most likely buys his Ferrari or Aston Martin first, but he also wants to acquire a less recognized but striking collectible, such as the Dusenberg, to round out his collection.”

The $10 million chameleon is part of Chopard’s burgeoning high-jewelry collection, which over the past few years has come to represent the house’s prowess in acquiring collectible gems and executing complicated designs. Other captivating jewels in the collection include a pair of intense-pink, pear-shaped diamond drop earrings and a 9.33-carat, deep-blue, oval-cut diamond set in a ring of rose gold and pink-diamond pave.

However, these mere colored diamonds, though extraordinary, can never match the private pleasure that a chameleon provides its wearer. “The mystery of the color change isn’t immediately evident to an observer,” says Moses. “The owner carries a secret that she can reveal only if she wants. But once you witness the color change firsthand”, he says, “you can’t believe your eyes, and you want to see it again.”


Source: Gems & Gemology, Thomas Hainschwang, Dusan Simic, Emmanuel Fritsch, Branko Deljanin, Sharrie Woodring, and Nicholas DelRe

Chameleon diamonds are among the rarest of gem diamonds. This article reports on a unique collection of 39 chameleon diamonds ranging from 0.29 to 1.93 ct, which exhibited temporary changes in color when heated to approximately 150ºC and, for some, after prolonged storage in the dark (i.e., thermochromic and photochromic color changes, respectively). Most changed from “olive” green to brownish yellow or yellow, although some changed from light yellow to a more intense greenish yellow.

The rarity of chameleon diamonds and their interest for the connoisseur are due to their unusual ability to change color temporarily when heated to about 150ºC (“thermochromism”) or after prolonged storage in the dark (“photochroism”). The stable color shown by chameleon diamonds is typically grayish yellowish green to grayish greenish yellow (“olive”). After heating, the color of a chameleon diamond quickly returns to its stable hue. Some of these chameleons have a stable color reminiscent of ‘normal´ green diamonds. While the green color of these diamonds is caused by exposure to radiation (either naturally or in the laboratory), the mechanism behind chameleon coloration is not yet well understood. Nevertheless, chameleons are among the few green diamonds that can be conclusively identified as natural color, since this behavior cannot be created or enhanced in the laboratory.


What is a chameleon diamond? Many people have never heard of it, let alone held one in their hands, such is its rarity. However, if you were to ask a collector, gemologist or a trader of previous stones, they would all tell you that the chameleon diamond got its name owing to its unique trait of changing color when heated or when kept for a prolonged period in a dark place.

So what does this exotic stone look like? If it has not been exposed to anything or been processed at all, then its color is usually olive or a grey yellowish green. When heated to 120 – 150 degrees, the olive tint of the diamond, within a matter of seconds, turns into a rich cinnamon or, in some cases, an orangy yellow (see below).

The change of color is visible to the naked eye, but practice has shown that this unusual characteristic is short-lived. This is especially the case if a chameleon diamond that has changed color because of its storage in the dark, within 10 minutes it regains its usual olive tint.

Incidentally, not all these diamonds change color from a dark hue to a light one. The so-called ‘reverse shift’ also exists, from yellow to olive. These stones are even rarer. Amongst other green diamonds, it sometimes hides this unusual quality, masquerading as an ordinary green diamond.

Until 1943, when the first chameleon diamond was recorded at the Gemological Institute of America (GIA), jewelers and diamond traders could have taken these ‘chameleons’ to be mere green diamonds. In order to determine accurately whether a diamond can change color, a laboratory experiment is required. This can be done at the GIA, where the approach to testing green diamonds is especially meticulous (if a tested green diamond is not a chameleon then, under a heat that exceeds 140 degrees, its hue can be changed permanently).

No one has managed to explain the color change phenomenon yet. Even the specialists at the GIA, who have run multiple simultaneous tests on 39 chameleon diamonds (the report is available on GIA website), cannot reach a unanimous opinion: some think the change of color is due a hydrogen impurity in the stone’s chemical composition; others believe that it has luminescent and phosphorescent properties. Of course, anything that cannot be explained is the subject of significant interest. That is why the specialists are continuing their investigative work in the hope of solving this mystery of nature.

You are probably already wondering what this “two-faced” stone can cost. Like all rare diamonds, the essential factor that determines price is size, as well as the tone and depth of color. The trouble is chameleon diamonds are so rare that to value them properly is quite difficult. Sales at auction currently serve as the best indication of their value. For instance, in November 2011 a chameleon diamond ring (8.8 carats) was sold by Christie’s in Hong Kong for $590,000. Chameleon diamonds under 2 carats are still affordable for the average individual seeking financial diversification.



Venezuela and West Africa share the same diamond geological formations – more proof that the American and African continents were originally joined together. These two regions are the only ones in the world that produce very distinctive neon greenish-yellow diamonds with a very high fluorescence, which stands out in an extraordinary way! These stones usually have an octahedral or dodecahedral shape and contain few impurities.

Types of diamonds produced in Venezuela: colorless, greenish-yellow, intense yellow, brown.

Types of diamonds produced in Ivory Coast: colorless, greenish-yellow, brown.

Diamonds in Venezuela and Guyana

The Amazonian craton consists of the Guapore Shield in Brazil and the Guyana Shield in southern Venezuela, Guyana, Surinam, French Guiana and Northern Brazil. It consists of several distinct geologic elements whose style of tectonism and age correlated to elements found in West Africa.

Alluvial diamond deposits in Venezuela and Guyana are mainly associated with the Roraima Formation. All rivers and streams that flow along or across the Roraima Formation contain diamonds. In Venezuela, the alluvial gravel of the Caronia, Paraguay and Cuyuni Rivers and their tributaries all contain alluvial diamonds.

Essentially all of the diamonds in Venezuela have been recycled from ancient river sediments. The very high proportion of diamonds in the Guaniamo deposits, and several features of the mineral inclusions in the diamond, show striking parallels to the Argyle deposit of Australia.

In Guyana, some crystals of diamonds found in alluvial deposits at the Mazaruni and Kurubrang Rivers and its tributaries have a thin brown to green outside layer (skin). This is characteristic of diamonds exposed to radiation for a long period of time. In Venezuela the total recorded diamond production between 1950 and 1968 averaged 100,000 to 120,000 carats/year. The discovery of the Guaniamo deposit increased the production of diamonds to 3.5 million carats between 1970 and 1974. By 1979, 77% of diamonds produced in Venezuela came from Guaniamo deposit.

Diamond Color and Transparency (Guaniamo)

The majority of the diamond crystals from the Guaniamo region are colorless: colored diamond colors include smoky-brown, grey and green. The smoky-brown color results from plastic deformation, whereas the grey color is caused by the presence of numerous black graphite-like inclusions (Orlov 1987). In addition to green-colored diamond, there is also green-spotted diamond. The La Centella placer contains a higher proportion of green diamond and fewer colorless and grey diamond.

The abundance of green, rather than brown, radiation spots, and the low level of abrasion on most crystals of diamond, suggest that most of the diamond crystals in the placers have had a short crustal history, and probably have been transported over distances no greater than 10 - 20 km. Even though these diamond crystals have travelled only a short distance, every attempt to locate the “motherload” has proved futile.

This report is based on information available to the public. The information and any statistical data contained herein has been obtained from sources we believe reliable, but we do not represent that they are accurate or complete and should not be relied upon as such. The material contained herein is for information purposes only.

Premier Diamond Group (North America) Lt

David Metcalfe


Source: EmailWire.Com

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