Natural Fancy Coloured Diamonds are one of nature’s most remarkable treasures. In themselves they are an unusual and rare find, but one diamond that is even more awe inspiring and fascinating is the Fancy Coloured Loose Chameleon Diamond. As its name suggests this amazing diamond possesses a unique power of being able to change its colour temporarily according its environment, very much like the reptile that is was named after, the Chameleon.
Fancy Coloured Loose Chameleon Diamond are one of the greatest mysteries of the gemological world and scientists still do not know the exact reason that these diamonds temporarily change colour and hues when exposed to heat or left in darkness.
The GIA first studied and recognised the existence of Fancy Coloured Loose Chameleon Diamonds in 1943, prior to these studies these diamonds were regarded as simply being green diamonds. The GIA carried out experiments and tests on 29 Fancy Coloured Loose Chameleon Diamonds to establish the differences between the Chameleon Diamonds and green gemstones. These tests showed that an ordinary green diamond when exposed to extreme heat will permanently change colour, whereas a true Fancy Coloured Loose Chameleon Diamond will be able to return to its original hue ( as its namesake does). They also categorised two basic types of Fancy Coloured Loose Chameleon Diamond which are graded as classic or reverse.
The vast majority of Fancy Coloured Loose Chameleon Diamonds are classic. This means that they have a stable body colour of greenish grey to greyish greenish yellow (olive) with brown or yellow undertones. When subjected to heat or a minimum of 24 hours in the dark, the stable body colour changes to an unstable body colour of yellow, orangey yellow or yellow with an olive green modifier.
Where Are Fancy Coloured Loose Chameleon Diamonds Found?
The exact origins of Fancy Coloured Loose Chameleon Diamonds remain unknown. However it is known that approximately 40% of these diamonds were purchased in India, 30% bought in Antwerp and 30% in Tel Aviv.
How Do Fancy Coloured Loose Chameleon Diamonds Change Colour?
The vast majority of Fancy Coloured Loose Chameleon Diamonds are small which makes them very difficult to study, however HRD Research had the opportunity to study an unusually large oval-shape diamond of this type weighing 4.89 carats.
Scientists noted that in its normal state the diamond had a greyish-green to greyish-olive appearance. However when kept in the dark for a considerable length of time or heated to up to 300°C, its colour changed to intense yellow.
It is known that the colouration of Natural Fancy Coloured Diamonds is caused by defects in the atomic scale within the crystal lattice of the diamond during formation. Scientists concluded that within the Fancy Coloured Loose Chameleon Diamond being studied, the colour change from greyish-green or greyish-olive to intense yellow was related to the presence of hydrogen and nickel impurities in the crystal lattice. It was seen that Chameleon Diamonds contain unusually high concentrations of hydrogen, as well as traces of nickel and nitrogen, in their crystal structure. This nitrogen-hydrogen complex therefore could be responsible for the chameleon effect. However, the actual physical mechanism behind this effect which is known as thermochromism (a switch in response to heat) and a photochromism (a switch in response to light) is still unknown.
What Is the Difference Between Classic and Reverse Fancy Coloured Loose Chameleon Diamonds?
There are two types of Fancy Coloured Loose Chameleon Diamonds ‘Classic’ and 'Reverse'. These categorisations basically describe the two distinct natural capabilities of these diamonds which are Thermochromic and Photochromic.
Fancy Coloured Loose Chameleon Diamonds exhibit Thermochromic behaviour. This enables the diamond to temporarily change to a darker colour when heated from 130°c to 230°c for a short period of time. As the Chameleon Diamond cools down its colour gradually changes back to the original lighter colour.
In contrast, as the name suggests, reverse Fancy Coloured Loose Chameleon Diamonds act almost exactly opposite to Classic Chameleon stones. The diamond’s Photochromic behaviour enables the stone to temporarily change from a darker to a lighter colour when stored in a dark place for a longer period of time, usually over 24 hours. When the stone is once more exposed to light, the darker colour is gradually restored. Reverse Fancy Coloured Loose Chameleon Diamonds do not have any reaction to temperature changes.
What Intensities and Shades Do Fancy Coloured Loose Chameleon Diamonds Come In?
Fancy Coloured Loose Chameleon Diamonds do not appear in all colour intensities. They are available in fancy light, fancy, and fancy deep and are not found in vivid and intense colours.
According to whether the Chameleon diamond is ‘classic’ or reverse’ defines its dominant colour which can be green, yellow, brown or grey. Fancy Coloured Loose Chameleon Diamonds always exhibit a degree of fluorescence and generally exhibit an overtone combination of colours (unlike Fancy Natural Coloured Diamonds).
Some of the more common overtone combinations are Brownish-Yellowish, Gray-Yellowish, Grayish-Yellowish, Gray-Greenish, Brownish-Greenish, and Green-Yellow. Similar to all Fancy Natural Coloured Diamonds, no two diamonds are exactly alike and many other colour combinations will be found. However, it should also be noted that there are a number of Fancy Coloured Loose Chameleon Diamonds that contain only one secondary hue, for example the 8.04 carat fancy dark grey- green Chameleon diamond discussed earlier.
Are Fancy Coloured Loose Chameleon Diamonds Expensive And Are They An Investment?
As can be imagined, the value of a Fancy Coloured Loose Chameleon Diamond is determined by its unique colour-changing properties, as opposed to the diamond's colour saturation or intensity as with other Natural Fancy Coloured Loose Diamonds.
The colour scale for Fancy Coloured Loose Chameleon Diamonds is divided into two which corresponds to their value. The first group is the more affordable Chameleon diamonds which feature a noticeable brown hue that is often referred to as a ‘muddy brown’. The clarity and lustre of diamonds in this group is generally of a lower quality. The second, more expensive group are those Fancy Coloured Loose Chameleon Diamonds that display an olive hue and show more brilliance and lustre.
Since Chameleon Diamonds are extremely rare, finding a large Chameleon is an almost impossible task therefore a large Fancy Coloured Loose Chameleon Diamond will be highly sought after by diamond connoisseurs or investors, easily commanding a price of at least six figures per carat.
Are There any Famous Fancy Coloured Loose Chameleon Diamonds?
Surprisingly despite their rarity there have been a number of famous Fancy Coloured Loose Chameleon Diamonds.The Chopard Chameleon Diamond is the largest documented Fancy Coloured Loose Chameleon Diamond. It weighs a very impressive 31.32 carats and is an oval-cut diamond that boasts exceptional clarity and colour and is heralded as an especially stunning example of the Fancy Coloured Loose Chameleon Diamond family.
Another remarkable Fancy Coloured Loose Chameleon Diamond that was discovered by Africa Gems is an 8.04-carat radiant-cut diamond. The GIA classified this fine example of a Chameleon diamond as being a fancy dark grey green. This diamond was set in a rose gold ring surrounded by a pave frame of small pink diamonds, and is estimated to be worth approximately $2,100,000. Africa Gems also found a Fancy Coloured Loose Chameleon Diamond weighing over 4 carats that is now set in a platinum ring. This piece of exquisite jewellery fetched an impressive $240,000 in a Hong Kong auction.
Where Can I Buy Fancy Coloured Loose Chameleon Diamond Jewellery?
As discussed previously, Fancy Coloured Loose Chameleon Diamonds are extremely rare and unique. Therefore they are not commonly found within high street jewellers but are sourced by specialist diamond experts.
So if you have set your heart upon investing in a Fancy Coloured Loose Chameleon Diamond consult the team at Rêve Diamonds of Hatton Garden, London who are one of only a very few diamond experts in the UK who can offer their valued customers the choice from an impressive collection of Fancy Coloured Loose Chameleon Diamonds.