COLORED DIAMONDS
The following overview of the most renowned naturally coloured diamonds, including red, pink, blue, green, orange, yellow, chameleon and purple, offers only a brief glimpse into the extraordinary world of fancy coloured diamonds. Each hue holds its own fascinating science, storied history and unique market significance, each profound enough to fill volumes on its own.
RED DIAMONDS
A fancy red diamond is considered the most coveted of all coloured diamonds and at the same time, the rarest of the naturally coloured varieties. Red diamonds are mined from only a limited number of locations worldwide, including Australia, Brazil, Russia, and India. Their extreme rarity means that gemmological documentation is scarce. What is known, however, is that crystal lattice distortions caused by stress during the diamond’s formation are the most likely explanation for the red hue.
Argyle Phoenix | Phillips Geneva
The famous “Argyle Phoenix” was sold to Laurence Graff, founder of Graff Diamonds, for more than double its estimated price. The hammer fell at 3.8 million Swiss francs (equivalent to 4.2 million US dollars, or 2.7 million dollars per carat).
PINK DIAMONDS
Until recently, the cause of the pink colour in diamonds remained a scientific mystery. What is known, however, is that unlike other coloured diamonds such as green, blue and yellow, the hue is not caused by trace elements within the diamond’s structure. Some researchers instead believe that an atomic defect in the crystal lattice selectively absorbs light, creating the pink tone. The exact cause, however, is still unknown.
The most significant mine for pink diamonds
A large share of the world’s pink diamonds comes from the Argyle mine in Australia, which is known for producing over 90% of all pink diamonds. This mine closed in 2020, further limiting supply and increasing their value. Pink diamonds from the Argyle mine have appreciated by as much as 500% over the past 20 years and are expected to rise even further.
Pink Star | Sotheby’s Hong Kong
Sold for 71.2 million US dollars in 2017 at Sotheby’s in Hong Kong, the Pink Star diamond remains the most expensive diamond ever sold at auction. Discovered by De Beers in Africa, it is a 59.60-carat oval-cut fancy vivid pink diamond with internally flawless clarity. In its rough form, it weighed an impressive 132.5 carats, and it took more than two years to cut and polish the stone into its current form. The auction was won by Chow Tai Fook Enterprises, a Hong Kong-based jewellery company, and the diamond continues to be regarded as one of the rarest in the world.
BLUE DIAMONDS
In recent years, two key factors have had a major impact on price development. First, the leading mine for blue diamonds has exceeded its maximum production capacity, resulting in a significant drop in supply. Second, vivid blue diamonds have repeatedly achieved record prices at auction a trend that has elevated values across the entire coloured diamond market.
When tiny boron particles become trapped within a diamond’s structure, they can give it a beautiful blue colour. Most blue diamonds belong to a category known as Type IIb, meaning they contain almost no nitrogen an element typically present in diamonds. Even rarer are diamonds whose blue colour is caused by hydrogen within the stone’s structure known as Type Ia. However, these diamonds are most often classified with colour modifications and are typically described in gemmological reports as grey-violet or grey-blue.
De Beers Blue | Sotheby’s Hong Kong
The De Beers Blue diamond sold for an astonishing 57.5 million US dollars at Sotheby’s in April 2022, setting the record as the most expensive blue diamond ever sold at auction. Weighing 15.10 carats, this Fancy Vivid Blue diamond is not only the largest of its kind ever offered at auction it is also the largest internally flawless step-cut vivid blue diamond ever graded by the Gemological Institute of America (GIA).
GREEN DIAMONDS
A green hue in a diamond means the stone has been exposed to natural radiation over millions of years. This radiation and in some cases the presence of hydrogen alters the diamond’s outer structure, creating a green colour.
What makes a true green diamond special is that the colour does not always permeate the entire stone. In many cases, the hue is only present on the surface or in patches, meaning it can disappear if the diamond is cut.
In the rarest cases, the diamond has been exposed to such intense beta and gamma rays, as well as neutrons, that the colour penetrates deep into its structure. These exceptional diamonds retain their green hue regardless of cutting and it is precisely these that command the highest value.
Most green diamonds originate from Brazil, Venezuela, and Zimbabwe.
ORANGE DIAMONDS
Orange diamonds are a rarity, almost an anomaly within the natural colour spectrum.
Is pure orange the most overlooked rarity?
Although orange as a colour is not as uncommon in nature as other hues, GIA rarely grades a diamond as solid orange without secondary tones. This means that diamonds achieving this classification are often even rarer than the famed pink diamonds.
The orange colour typically arises from the presence of nitrogen atoms, which influence how the stone absorbs light and create its warm, saturated tone. In certain rare cases, however, the colour may also be caused by structural distortion within the diamond’s crystal lattice, known as lattice distortion, which changes how light is absorbed and reflected.
The rarest stones, known as pure orange or pumpkin orange, are believed to result from an almost perfect balance between nitrogen influence and subtle lattice distortion.
For a diamond to be classified as a Fancy Orange Diamond, it must not contain brown and only a very small amount of yellow.
YELLOW DIAMONDS
Yellow diamonds are the most popular among all naturally coloured diamonds, and by far the most commonly produced fancy coloured diamonds. It is estimated that around 74% of all naturally coloured diamonds fall into the fancy yellow category.
A fancy colour yellow diamond falls outside of the GIA’s D-to-Z colour scale. Most colourless diamonds are graded based on how little colour they contain the more colourless, the more valuable according to the GIA scale from D to Z. Yellow diamonds categorised as “fancy colour” display more colour than what is seen at the Z end of the scale. Unlike colourless diamonds, the value of fancy coloured diamonds increases with the strength and purity of their colour.
What gives the yellow colour?
A yellow diamond owes its hue to the presence of nitrogen atoms within the diamond’s crystal lattice. Nitrogen absorbs some of the blue light in the visible spectrum, causing the diamond to appear yellow to the eye. The more nitrogen present, and the more concentrated it is in the structure, the more intense the yellow colour becomes.
CHAMELEON DIAMONDS
The Diamond with Two Faces
Chameleon diamonds are a rare scientific phenomenon known for their remarkable ability to change colour under certain conditions. When heated or kept in darkness, they temporarily shift in hue, typically from greenish to yellow or brownish tones. When cooled or exposed to light, the colour returns to its original state.
This extraordinary behaviour is caused by unique structural characteristics within the diamond’s crystal lattice and the presence of specific trace elements. Genuine chameleon diamonds are extremely rare and highly prized among collectors for their natural mutability and mysterious allure.
Most chameleon diamonds found today originate in small quantities from mines in Sierra Leone, Congo and Central Africa.
PURPLE DIAMONDS
Purple diamonds rank among the rarest colours found in nature and occur only in a few mines worldwide. The colour is created by plastic deformations within the crystal lattice during the diamond’s formation deep within the Earth, where immense pressure and heat produce a subtle fusion of blue and pink tones.
The hue ranges from delicate lavender to deep violet and is often described as a blend of elegance and mystery. The most sought-after purple diamonds originate from the Argyle mine in Australia, where some of the world’s most vivid and pure purple shades were discovered before the mine’s closure in 2020.
Today, purple diamonds are considered true collector’s gems, cherished for their rarity, complexity and natural beauty.
