When it comes to diamonds in general rarity equals value. With normal diamonds the value is based on the absence of colour with colourless diamonds being the rarest. On the other hand, we get fancy coloured diamond’s where the saturation of the colour is the most significant characteristic and adds to the rarity of the diamond. In fact, unlike a colourless diamond where the 4C’s “carat weight, clarity, colour, and cut,” are all equally important to the overall value, the fancy coloured diamonds colour characteristic plays the most important role in the value of the diamond.
Yellow diamonds are of the most common among the coloured diamonds and are less costly. There is a rather high demand for yellow diamonds which is closely followed by the pink diamond. Most of the time the demand of coloured diamonds fluctuates depending on which celebrity is seen wearing the diamond – I mean, who doesn’t remember Jennifer Lopez’s 6.1-carat pink Harry Winston diamond engagement ring worth a reported $1.2 million.
Second on the list is the Green Diamond. The green colour is caused by exposure to atomic radiation or radioactivity making it extremely unique. So much so, that it is somewhat difficult to determine whether a green diamond is natural or treated, which is very hard to determine. Many polishers purposely leave a section unpolished along the girdle of the stone so that diamond associations, such as the GIA, can identify the natural colour of the stone and thereof award it a certified diamond certificate.
The most famous green diamonds must be the 40.70 carat pear shaped VS1 rated Dresden Green diamond. It is the largest, and perhaps the finest, green diamond known to have a colour of natural origin and is reported as one of the largest and finest natural green diamond ever discovered.
Third on our list of rare colours is the orange diamond of which the most famous is the Pumpkin Diamond weighing in at 5.54 carats which was bought and named by The House of Harry Winston at a price of $1.3 million dollars.
Just like yellow diamonds, orange diamonds get their colour from nitrogen. The difference is however that to produce an orange colour, the atoms must be aligned in a very precise way which lends to the rarity of the stone. So far only mines in Australia and in Africa have ever produced orange diamonds.
Pink diamond comes up on our fourth rarest of diamond colours and arguably the most beautiful of colours. The way in which the pink diamond gets its colour is still somewhat of a mystery although scientists speculate that the stress and strain experienced by rough diamonds when they are in the Earth’s mantle causes the diamond’s lattice to be distorted. This distortion creates graining and pink colour zones to occur within the diamond. The pink diamond holds the title of the most expensive gem ever sold at auction, the fancy vivid pink diamond known as the Pink Dream or Steinmetz Pink, weighing in at 59.60 carats sold for $83 million dollars.
Following on with the rarity of colour we have the second rarest colour, the blue diamond. The blue diamond gets its colour from the presence of boron. Boron is a chemical element produced entirely by cosmic ray spallation and it is a low-abundance element in the Solar system and in the Earth’s crust. The most famous of blue diamonds and jewellery pieces in fact is the Hope diamond. The Hope diamonds ownership dates back almost four centuries. Weighing 45.52 carats, its exceptional size has revealed new findings about the formation of gemstones.
The rarest of diamond colours is the red diamond, in fact red diamonds are so rare that there is little gemmological information about them. What is known however is that crystal lattice defects showing stress lamination during the diamond’s formation are the main cause of the red colour. While pure red diamonds are almost non-existent they do come in a purplish to brownish red colours. Combine these colours with high clarity, cut and carat and you have a near priceless diamond.