ABOUT NATURAL FANCY COLOUR DIAMONDS
Although exceptionally rare, natural fancy coloured diamonds of all colours can be found in nature – from red (the most rare and valuable) to pink, blue, green, orange, green, yellow and brown. These fancy coloured diamonds lie outside the white colour range and are extremely rare and valuable. There is only one natural fancy coloured diamond discovered for every 10,000 colourless diamonds.
The formation of natural fancy coloured diamonds requires the presence of additional trace elements and distortions to the typical diamond crystal. If an element interacts with carbon atoms during the creation of a diamond, the diamond’s colour can change. There are three ways in which natural fancy coloured diamonds are formed. The fancy coloured types of diamonds are grouped into Type I, Type II and Type III Diamonds.
The Types of Diamonds
Type I Diamonds
Type I diamonds are formed when a foreign element is introduced to the carbon material that a diamond is made from. For example, nitrogen can cause a diamond to have yellow or orange hues while boron can make it blue. Diamonds with nitrogen (N) atoms in their internal atomic structure comprise the most abundant group of diamonds. The nitrogen in fancy coloured diamonds absorbs colour, and this difference makes them yellow and orange. Nitrogen also is linked to colour in brown diamonds, in some blue and green diamonds, as well as in pink diamonds.
Diamonds in the nitrogen group comprise 98 percent of all natural fancy colour diamonds. The nitrogen group is divided into different types, called IaAB, IaA, IaB and Ib, depending on the way nitrogen bonds with carbon in the diamond’s internal structure.
Type II diamonds
The second group is very rare. These diamonds are almost 100 percent nitrogen free, and comprise only 2 percent of all diamonds. These diamonds occur when pressure compresses the carbon and creates a red, pink or purple hue. This group is further divided into IIa and IIb diamonds.
Type IIa diamonds are the purest diamonds in nature, and consist almost completely of carbon. These can be colourless, brown or pink.
Type IIb diamonds, ultra-rare and nitrogen-free in this type II group, become natural fancy blue diamonds. These contain boron (B) atoms in their structure, and it is this boron in the otherwise pure carbon atomic structure, that is responsible for the blue colour in fancy colour blue diamonds.
Type III Diamonds
The third group refers to those diamonds that receive their colours by other means that are not well understood, but known. The best example is green coloured diamonds. The colour of these stones is derived from an exposure to radiation.
When it comes to diamonds, rarity equals value. For every 10 000 colourless diamonds mined, only one natural fancy colour diamond will be discovered. Natural fancy colour diamonds are extremely rare and tend to be found mostly as small diamonds weighing less than a carat.
Unlike colourless and near colourless diamonds which are valued for their lack of colour, natural fancy colour diamonds are valued precisely for their intensity and distribution of theirs.
The formation of natural colour diamonds requires not only the special conditions necessary for the creation of all diamonds, but also the presence of additional trace elements and distortions to the typical diamond crystal. If an element interacts with carbon atoms during the creation of a diamond, the diamond’s colour can change. Radiation and pressure on a diamond’s structure will also have an impact on its colour.
Up until the 16th century, the most well-known historical diamonds, including fancy coloured diamonds, all came from India. The most well-known historical and current sources of natural fancy colour diamonds are from India, South Africa and Australia. Other diamond mine locations that produce natural fancy colour diamonds include Brazil, Venezuela, South America, Russia, and Indonesia.
The following countries are known to supply various natural fancy colour diamonds:
- Orange Yellow
Australia Argyle Mine
Natural fancy coloured diamonds come in a vast array of different colours. There are 27 officially recognised coloured diamonds.
Natural red fancy colour diamonds are the rarest of the coloured diamond collection and are highly valued. Some say there may be less than 20 true red diamonds in the world. Only a handful have ever received the grade of fancy red, a red diamond in its purest form. Its red colour is caused by a process known as ‘plastic deformation’, a slipping or distortion of the atomic lattice.
Blue diamonds represent only 0.1% of all natural fancy coloured diamonds, making them extremely rare and valuable. Blue natural fancy colour diamonds generally have a slight hint of grey. Their colour is typically caused by the presence of boron. The higher the concentration of boron, the more intense and deeper the colour. Some greenish blue diamonds have been discovered that lack boron; it is thought that their blue colour is due to natural radiation that would have been present when they formed. Very rarely, a greyish blue colour is caused by the presence of hydrogen.
Exactly what gives a natural fancy pink diamond its colour is still something of a mystery. Studies have shown that most pink diamonds contain graining lines within their atomic structure caused by pressure beneath the Earth’s surface. This is referred to as ‘plastic deformation’, meaning the growth of the crystal lattice has been compressed, affecting the way light refracts within the gem. Scientists believe graining is due to the tremendous pressures to which diamonds are subjected under the earth’s surface. Different levels of graining will result in different shades and is also thought to produce red diamonds. With only an estimated decade of supply remaining, Pinks diamonds are becoming increasingly precious.
Like natural fancy pink and red diamonds, natural fancy purple diamonds are coloured by minute graining within the diamond structure. The resulting shades vary from pale orchid to deep imperial purple. As purple is a colour intermediate between red and blue it can display both warmth and cool effects. Although pure purple diamonds are very hard to come by, many are available with a grey or pinkish modifier, and other coloured diamonds can display a purplish secondary hue. Most purple diamonds tend to be small, generally weighing 2 carats or less.
Natural fancy green diamonds are typically light in town and low in saturation. Their colour often appears muted, with a greyish or brownish cast. The hue is often confined to the surface and rarely extends through the entire diamond, which is why cutters try to leave as much of the natural rough around the girdle as possible. Natural fancy green diamonds derive their colour from exposure to gamma rays deep below the earth’s surface over a long period of time, possibly even as long as millions of years. This happens naturally; radiation displaced atoms from their normal position in the crystal lattice. Very rarely, hydrogen may also cause some greyish green stones to form. This can create an interesting subset of Green diamonds known as Chameleons. As the name suggests, Chameleons are naturally changeable stones whose shades shift when subjected to different temperatures.
Ranging from pale translucent saffron to fiery autumnal hues, natural fancy orange diamonds are predominantly found in South Africa. Their colour is caused by the presence of nitrogen. Pure orange, with no hint of brown, is one of the rarest colours and is most likely the result of a combination of nitrogen atoms and structural deformities.
Yellow diamonds are the second most common natural fancy colour. Their yellow colour is caused by the presence of nitrogen. A particularly yellow diamond whose colour is deeper, more intense or more vivid than a Z colour diamond moves from the ranks of common colourless diamonds to the rarefied realm of fancy coloured diamonds.
Brown is the most common natural fancy colour diamond and also the earliest to be used in jewellery. Romans set brown diamonds in rings, but in modern times it took a while to become popular. Until the 1980s, brown diamonds were typically considered good only for industrial use. The Australians fashioned them and set them into jewellery, marketing them with names such as “cognac” and “champagne”, which increased their popularity. Brown diamonds range in tone from very light to very dark, with consumers generally preferring the medium to dark tones with a warm, golden appearance. They generally show a hint of greenish, yellowish or reddish modifying colour.
COLOUR GRADING (GIA GTL SYSTEM)
Grading natural fancy colour diamonds is complex and specialised, and it takes highly trained laboratory graders to complete the process accurately. GIA’s processes for evaluating coloured diamonds involve multiple graders and the same item identification and tracking procedures used in diamond grading.
GIA offers two types of grading reports for fancy coloured diamonds. The GIA Coloured Diamond Grading Report contains the same comprehensive diamond 4Cs information as the GIA Diamond Grading Report, while the GIA Coloured Diamond Identification and Origin Report (also known as the colour-only report) is limited to colour grade and the origin of the colour (natural or treated).
The GIA system for colour-grading fancy colour diamonds is designed to accommodate the fact that not all coloured diamonds have the same depth of colour. (E.g. yellow diamonds can occur in a wide range of saturations, while blue diamonds do not.)
Fancy coloured diamonds are also valued based upon the four C’s but another factor weighs most heavily on the value of a fancy coloured diamond. This factor is based upon the hue and rarity of the colour. A rare fancy colour will garner a much higher price than a colourless diamond of a higher carat weight.
Fancy coloured diamonds have three characteristics by which they are graded. These are hue, tone and saturation. Hue refers to the dominant colour of a diamond, such a pink, yellow, blue, green, etc. Tone represents how light or dark a diamond appears, depending on how much brown, black, grey or white is present. Saturation refers to the colour’s depth or strength. The saturation of lightly tones diamonds can vary from light to intense and vivid. Darker diamonds will range from deep to dark in description. Using highly controlled viewing conditions and colour comparators, a fancy colour grader selects one of 27 hues, then describes tone and saturation with terms such as "Fancy Light," "Fancy Intense," and "Fancy Vivid." The colour system GIA developed is used worldwide.
FAMOUS FANCY COLOUR DIAMONDS
Some of the world’s most famous diamonds are natural fancy colour diamonds, rich in history, legends and beauty.
The Hope Diamond
|Colour: Natural fancy Dark blue
Shape: Oval brilliant
Origin: Unknown, but believed to originate from India
The Hope Diamond is widely considered to be one of the most famous natural fancy colour diamonds in the world, surrounded by many fables and legends. Its large size (45.52ct), rare dark blue colour and flawless clarity and beauty make it an intriguing diamond. With a history that spans over three centuries, the Hope Diamond was reputedly used to adorn the forehead (or eye) of a statue of the Hindu goddess Sita. According to the legend, it was stolen from the statue several centuries ago, and this was the start of the fabled curse, which foretold bad luck and death not only for the owner, but for all who touched it. The diamond had many owners and settings including a theft, a stint in the French Crown Jewels, two re-cuttings, an English King and a wealthy American socialite. It currently resides at the Smithsonian Institution. On 18 November 2010, the Hope Diamond was unveiled in a temporary newly designed necklace called “Embracing Hope”.
Moussaieff Red Diamond / Red Shield
|Colour: Natural Fancy Red
Originally known as the “Red Shield”, the Moussaieff Red is a triangular brilliant cut or trilliant-cut, fancy red, internally flawless (IF), 5.11ct diamond and is the largest red diamond in the world today. It was discovered in the 1990s by a Brazilian farmer in the Abzetezinho River. The rough diamond weighed 13.9 carats. In 2001, the Moussaieff jewellery firm acquired this diamond for $8million (approximately R74million).
The Pink Star Diamond (Pink)
|Colour: Natural Fancy Vivid Pink
Shape: Mixed oval brilliant
Origin: South Africa
Considered to be the finest natural fancy pink diamond in the world, the 59.60 carat Steinmetz Pink (formerly known as the Steinmetz Pink Diamond) is the largest known diamond having been rated a Vivid Pink. It was mined in 1999 in South Africa, weighing 132.5 carat in the rough and took 20 months to cut. It was unveiled in Monaco on 29 May 2003 in a public ceremony. The Pink Star Diamond was sold privately in 2007 but neither the identity of the buyer nor the price is on public record.
|Colour: Natural Fancy Brownish-Yellow
Origin: Democratic Republic of Congo
Weighing 407.48 carats, the Incomparable is the world’s largest fancy colour diamond and the third largest diamond ever cut, surpassed only by the Cullinan 1 and the Golden Jubilee. The diamond is remarkable for its internally flawless clarity, its unusual triangular shape, called a ‘triolette’, and its fancy brownish-yellow colour.The Incomparable was discovered in the Mbuji Mayi district of the Democratic Republic of Congo (formerly known as Zaire), almost a decade before the Millennium Star was discovered in the same region.
The Golden Jubilee Diamond
|Colour: Natural Fancy Yellow Brown
Shape: Cushion Cut
Origin: The Premier Mine, South Africa
The Golden Jubilee is the largest faceted diamond in the world, weighing 545.67 carats. Gabi Tolkowsky, who also designed the 273.85 carat Centenary Diamond, designed the diamond. The Golden Jubilee was purchased from De Beers by a syndicate of Thai business men, and presented to the King of Thailand in 1997 for his Golden Jubilee, the 50th anniversary of his coronation. Prior to this event, the stone was simply known as the Unnamed Brown.
Dresden Green Diamond
|Colour: Natural Fancy Green
Shape: Irregular Pear-shape
The Dresden Green diamond is the largest natural fancy green diamond in the world and was named after the capital of Saxony where it was exhibited for almost two centuries. The first written trace of this diamond dates back to 1726 when Baron Gautier, an evaluator in Dresden, refers in a letter to a green diamond that was proposed to King Frederic August I by a London merchant. Others say a Dutchman named Delles sold it to Frederic August II during a commercial fair in Leipzig in 1741. It is said that the rough diamond was purchased in Golconde by the famous diamond merchant Marcus Moses, who would have had it cut in London shortly before 1741. Seized by the Soviets at the end of the Second World War, the Dresden Green was returned to the Germans in 1958. Today, it is kept in the Albertinium Museum in Dresden.
BEST DIAMOND CUTS FOR FANCY COLOUR DIAMONDS
Natural fancy colour diamonds are cut to maximise the intensity of their colour rather than to maximise brilliance and light return. The best cut for a fancy colour diamond is one that gives the most attractive face-up colour. This is why fancy colour diamond are often cut into fancy shapes, such as radiant, cushion, pear or oval, which amplify colour. Although round brilliant cuts are worth more than fancy shapes because there is a higher loss in weight, the colour is not maximised. While fancy colour diamonds still exhibit brilliance, the most important characteristic considered is colour.
Certain cuts, such as the radiant or cushion, intensifies the colour in a diamond. When cut as a radiant cut, many yellow-tinted stones can become fancy yellows when viewed face up. This perceived improvement in colour increases the price per carat. The radiant cut also gives a higher yield from the rough compared to a standard round brilliant.
NATURAL FANCY COLOUR DIAMONDS VS ARTIFICIALLY
TREATED COLOUR DIAMONDS
A man-made method to produce fancy coloured diamonds involves irradiating a natural diamond. Irradiation is a process in which a diamond is exposed to a source of radiation that changes the position of atoms within the stone, causing its colour to change.
Lower quality white diamonds are used to synthesize a given colour. The appreciation and value of a treated diamond cannot be compared to a natural fancy coloured diamonds whose value continues to appreciate. Treated diamonds are mere imitations mass-produced and sold at low-cost.
There are some methods to determine whether a diamond is naturally coloured or if it has been treated. Here is how you can tell if a diamond is real. In many cases natural fancy coloured diamonds have very distinctive internal features. The diamond can be examined at various magnifications – a hand lens or a microscope – and a source of ultraviolet radiation to determine whether the diamond in question is naturally coloured or treated.
Further Reading: 25 Interesting Facts About Diamonds