By Rubina Posh January 21,2017
Chameleon Diamonds are the only diamonds that have the ability to temporarily change their natural colour. The ones with the more intense colour will be rarer and more expensive.
A 1.01ct SI2 Round Cut Diamond graded as Natural Chameleon was available on 8th December 2017 for around AUD$14,000
“Chameleon” is a natural colour classification just like blue or green and these colour changing diamonds known as Chameleon Diamonds are also colour graded as having a chameleon colour.
They are divided into eight categories:
2. Very Light
4. Fancy Light
6. Fancy Intense
7. Fancy Vivid
8. Fancy Deep/Fancy Dark
These are then further divided based on their secondary colours.
Always graded face up (flat side up) these diamonds will have the secondary colour listed first, followed by the main colour. The last colour mentioned is the most dominant colour.
Chameleon Diamonds are extremely rare and least known. Their behaviour cannot be copied/replicated and there is no known treatment to cause the chameleon effect on other diamonds or to state the cause of their colour. As a result of the rarity, their demand and price is higher.
To date, light and heat are the result of their colour changing abilities, however, there is no known scientific explanation as to why. They do however have an unusually high concentrations of hydrogen, and traces of nickel and nitrogen, in their crystal structure.
There are two types of Chameleon Diamonds.
The most common are the ones that change colour when they are heated from 100° Celsius to 250° Celsius, for a short period of time. Within a few seconds of heating the colour change begins generally around 100°Celsius – 140°Celsius with its most intense colour noticeable at 140°Celsius. The colour is evenly distributed however some of the diamonds may have patchy colour zoning. As they start to cool down, the colour slowly returns to their original colour. The colour of these diamonds changes from a lighter shade to a darker shade and back to their original lighter shade again.
The second type of Chameleon Diamonds when stored in a dark place for a longer period of time, change their colour to a lighter shade and when exposed to light, the original colour slowly returns. However, these chameleon diamonds have no reaction to temperature changes.
Their colour changes from a darker shade to a lighter shade and then back to their original darker shade again.
All Chameleon Diamonds have fluorescence whether slight, medium or strong. They are green, yellow, brown or grey with at least two overtones. Some of the more common overtone combinations include:
Brownish-Yellowish, Brownish-Greenish, Greyish-Yellowish, Grey-Greenish,and Green-Yellow.
Like all diamonds, there are no two diamonds exactly the same and many other colour combinations can be found.
In 1943 the GIA tested 29 diamonds to find out the difference between the typical green diamonds and chameleon diamonds. Before then it was assumed that they were all green. When the typical green diamonds are exposed to extreme heat they permanently change their colour, whereas the chameleon diamonds will be able to return to their original colour.
The origin of these gems is unknown except that approximately 40 percent of these diamonds were provided from India, 30 percent from Antwerp and 30 percent from Tel Aviv.
So basically, the only way to tell chameleon diamonds apart from other green diamonds is by their colour changing ability and the combination of the above-mentioned overtones.