Tailor-made and unique high-end jewelry starts with a one-of-a-kind diamond. Only 1 out of 10,000 carats that are mined today receives the name “Fancy Colored Diamond” by a reputable gemmological lab like the GIA (Gemmological Institute of America). This rarity makes them very desirable, and they can reach extremely high values.

 

 1. Rarity factor, value, and colors

Diamonds are known to be colorless (or light yellow/brown), as they represent 95% of the diamonds mined every year. But they actually occur in every color of the rainbow. If a diamond displays a colour other than light yellow or light brown/grey in the face-up position, it falls into the category “Fancy Colored Diamonds”. Many of these fancy diamonds are extremely rare, with the rarest colors being red, pink, orange, purple, and blue.

 

2. Source of color in diamonds & diamond types

The origins of the many colors in diamonds can be explained by their atomic structure. The ideal crystal lattice structure of a diamond is built up out of carbon atoms, arranged in an orderly three-dimensional structure. Each carbon atom is surrounded by four other carbon atoms forming a tetrahedron. An ideal diamond, fully built of carbon atoms, would be completely colourless.

In reality, however, a diamond structure contains a lesser or greater degree of atomic impurities and structural variations. These deviations from the ideal structure (called "defects") are known as "colour centres". The impression of a certain colour is therefore due to the concentration and the nature of the colour centres present in the diamond. An important cause of defects is the substitution of a carbon atom ("C") by a foreign atom. Other colour centres do not contain foreign atoms but, for example, vacancies, which are places where one normally finds a carbon atom, but which is now empty.

The most commonly occurring impurity atom in diamond is nitrogen ("N"). Depending on its occurrence in the diamond lattice, diamonds are divided into two groups. Type I diamonds that contain a detectable quantity of nitrogen and type II diamonds that contain practically no nitrogen.

In the table below, a short overview of the various types of diamond is given according to colour centres.

3. Facts about the different colors

• Fancy Yellow

Fancy yellow diamonds are the most common form of Fancy Colored Diamonds. They have gained huge popularity because of their sunny shine and their relatively affordable prices, compared to other colors.

Just like colorless diamonds, yellow diamonds come in all cuts and shapes (round, oval, cushion cut, asscher cut, princess cut, etc.) and sizes, and even in various color saturations and intensities (from light yellow to the rare and expensive intense and vivid yellow color grades).

Yellow diamonds’ color is due to the presence of nitrogen in their crystal structure. Depending on the amount of nitrogen, yellow diamonds range from light to vivid. Some brown or orange overtones can be found in fancy yellow diamonds.

Yellow diamonds are sometimes called “Canary Yellow” (not an official term used by gemmological laboratories) when they exhibit a very high saturation. They are the most sought-after and valuable type pf yellow diamonds. Just like the bird, they exhibit an intense yellow hue.

Intense fancy yellow diamonds are mostly found in South Africa. 

• Fancy Pink

Natural pink diamonds are among the most valuable and rare treasures on Earth. Top colored stones (graded “intense” and “vivid” on the GIA's colour scale) can fetch more than $2 million per carat at major auctions. Such prices come from their rarity as much as their beauty as only a tiny percentage of diamonds have a rich intense or vivid pink colour (the majority being brownish, brownish pink or champagne).

Since its opening in 1983, the Argyle diamond mine in Western Australia has taken a mythical status as the World’s premier source of pink and red diamonds. The rare colour in these highly prized diamonds are caused by tiny impurities trapped within the crystal’s structure when it is being formed deep within the earth.

The Argyle mine is responsible for producing more than 90% of the world’s high quality pink and red diamonds, yet fewer than 1% of the stones found at the mine are of this colour. In some extreme cases very large flawless, vivid pinks from the Argyle can fetch over £1 million per carat at auction. In fact, more than 80% of the stones produced at this site are brown (marketed as "Chocolate" diamonds), including the increasingly popular "Champagne" diamonds. 

When you consider that the 1% pink and red production accounts for over 90% of the global supply of these colours, you realize how scarce they are. Every cut & polished deep pink diamond produced at the Argyle in a year would fit in a Champagne glass!

The Argyle mine has closed for good in November 2020, leaving an uncertain price legacy for its highly coveted stones.

Discover Laurence's exclusive jewelry capsule Pink Up Your Love collection set with natural intense pink diamonds from the Argyle mine. It is the ultimate gift of love.

• Fancy Blue

Blue diamonds owe their mesmerizing blue tone to the presence of boron in the diamond’s crystal structure—the more boron, the deeper the blue. They range in color from light blue to intense blue, with sometimes violet, gray or green as secondary tone. Blue diamonds are real earth’s treasures and are no treated to enhance their color.

Blue diamonds are extremely rare and only found in a few mines in the world: the Goloconda mine in India, the Argyle Mine in Australia, and the Cullinan mine in South Africa.

Their value is dictated by the intensity of their color as well as by their carat weight. Because of their rarity, they are more expensive than pink, yellow and colorless diamonds.

Blue diamonds can be confused with sapphires, which are entirely different gemstones. Sapphires belong to the corundum family and contain traces of titanium, iron, magnesium, chromium and copper.

 

• Fancy Green

Fancy green diamonds are usually light in tone and mainly mixed with a gray or brown overtone. The hue is typically yellowish green.

Commonly, the green hue is located on the surface and rarely extends through the entire gemstone. This fact leads cutters in the cutting process to leave the main part of the rough around the girdle. But how do green diamonds get their unique color?

When a radiation process takes place, it displaces carbon atoms from their normal positions in their crystal structure. This happens during a natural process when diamond deposits lie close by radioactive rocks or artificially when stone undergo an irradiation treatment in a lab.

Green diamonds are one of the rarest fancy colored diamond types. And because of the possibility to perform an irradiation treatment to enhance their color, green diamonds are always examined carefully in gemmological laboratories. However, theses ones can’t sometimes determine their origin even with advanced gemmological equipment.

 

4. The importance of a grading report mentioning the intensity of the color

Grading fancy coloured diamonds is a complex process, seeing they are mainly valued for the intensity, distribution, and purity of their colour. The diamond cut and clarity also need to be taken into account, but are of less importance. Only highly trained lab graders can perform the task of describing accurately the color of a diamond.

The GIA color grading system has been set up with as base that each colored diamond has a different depth of color. They then add numerous nuances in all different colours going from Fancy Vivid (the most expensive diamonds), Fancy Intense, Fancy Deep, Fancy Dark, Fancy, Fancy Light, Light, Very Light and Faint (the least expensive diamonds). For fancy colored diamonds, the general rule is that the stronger the hue, the more valuable the stone becomes.

 

5. Diamond color treatments

With advances in technology, there are various types of artificial treatments and enhancements that can be used to alter a diamond’s color completely. Some of these methods will permanently change the diamond’s appearance, whilst others are only temporary measures. These “treated” diamonds loose of course some value compared to the natural colored diamonds which have not been treated at all. Color treatment should always be mentioned in a laboratory grading report (most of the time, a lab will emit a specific grading report for color-treated diamonds).

HPHT treatment is probably the most well known method to change the color of a diamond on a commercial basis. With proper control of the process, HPHT can be used to lighten the tint or saturate the existing tone of a lower grade diamond.

For example, heat and pressure treatment can turn a yellowish looking stone into a fancy colored one to increase its appeal. By making some tweaks in the process recipe, the same technique can also be used to turn brownish diamonds into colorless stones.

Another treatment is the irradiation process which uses nuclear reactors to bombard a diamond’s crystal lattice with radiation rays and forces the rearrangement of the carbon atoms. Irradiation process can be used in combination with HPHT treatment in a 2-step process. Typically, they are combined to create geen, blue, brown, yellow and black diamonds.