COLORED DIAMONDS
The following overview of the most well-known naturally coloured diamonds – red, pink, blue, green, orange, and yellow – represents only a microscopic glimpse into the fascinating world of fancy coloured diamonds. Each colour holds its own in-depth science, history, rarity, and market perspective, each of which could fill entire books 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 had 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 precise 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 in the natural colour spectrum.
Is pure orange the most overlooked rarity?
While orange as a colour is not as rare in nature as some others, the GIA seldom grades a diamond as “pure orange” without undertones of other hues. This means that diamonds which actually receive this classification are often even rarer than the famed red diamonds.
For a diamond to be classified as a fancy orange diamond, it must contain no brown and only a very small amount of yellow. True orange diamonds are, in fact, rarer than green, pink, or blue ones – but because orange is not a primary colour and sits close to yellow on the spectrum, demand is often lower. For this reason, collectors tend to prioritise other colours such as red, blue, pink, or green.
As with red diamonds, there is relatively little gemmological research on orange diamonds, precisely because they are so rare. What is known is that most orange diamonds have a darker tone and only weak to moderate colour saturation.
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.
