What Is a Purple Diamond?
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A natural diamond with a violet to purplish colour
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One of the rarest diamond colour categories
A purple diamond is a natural diamond whose body colour appears violet, lilac, or purple. Unlike coloured gemstones such as amethyst, the colour in a purple diamond does not come from chemical impurities in the usual sense. Instead, it comes from structural changes inside the diamond itself.
Purple diamonds are considered fancy colour diamonds, a category that includes blue, pink, green, and red diamonds. Among these, purple diamonds are exceptionally rare. Many stones described as “purple” are actually pink or grey diamonds with secondary purple tones.
True purple diamonds are so scarce that they make up far less than one percent of all fancy colour diamonds discovered.
How Does a Purple Diamond Form?
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Forms under extreme pressure deep within the Earth
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Colour caused by crystal lattice distortion
All diamonds form deep within the Earth’s mantle, typically more than 150 kilometres below the surface, under temperatures exceeding 1,000°C. Purple diamonds follow the same basic formation process as colourless diamonds, but with a critical difference.
The purple colour is caused by plastic deformation of the diamond’s crystal lattice. This happens when immense stress twists the atomic structure during or after formation. Light passing through the distorted lattice is absorbed differently, producing purple tones.
This same process is responsible for many pink diamonds, which explains why purple diamonds often show pink or grey undertones.
Where Is Purple Diamond Found?
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Found in very limited geographic locations
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Historically associated with a single major mine
The most famous source of purple diamonds was the Argyle mine in Western Australia. This mine produced over 90 percent of the world’s pink and purple diamonds during its operation.
Small numbers of purple diamonds have also been reported in Russia, South Africa, and Brazil, but these occurrences are extremely rare and inconsistent.
Since the Argyle mine closed in 2020, the supply of new purple diamonds has dropped dramatically, increasing both rarity and value.
Properties of Purple Diamond
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Exceptional hardness and durability
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Colour varies from soft lilac to deep violet
Purple diamonds share the same physical properties as all diamonds. They rank 10 on the Mohs hardness scale, making them the hardest natural material known. This makes them suitable for everyday jewellery wear.
Their colour can range from pale lavender to rich grape tones, sometimes appearing more intense under certain lighting. Many purple diamonds show colour zoning or uneven distribution, which is considered part of their natural character.
Name Origin
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Named purely for its colour
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No historical or mythological naming
Unlike many gemstones, purple diamond does not have a poetic or ancient name. It is simply named for its dominant visible colour.
In professional grading, purple diamonds may be described with modifiers such as “purplish pink” or “reddish purple”. A diamond classified as “Fancy Purple” without modifiers is extremely rare and highly prized.
The simplicity of the name reflects the stone’s straightforward classification rather than its rarity.
Pricing and Value of Purple Diamonds
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Among the most expensive coloured diamonds
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Prices driven by rarity and colour purity
Purple diamonds command very high prices. Even small stones can sell for substantial sums if the colour is strong and evenly distributed.
As a general reference, fancy colour diamonds often range from tens of thousands to hundreds of thousands of pounds per carat. For purple diamonds with strong saturation and no secondary colours, prices can exceed this range significantly.
Since supply has effectively stopped, purple diamonds are increasingly viewed as long-term collector stones rather than retail jewellery items.
History of Purple Diamond
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Long overlooked due to misclassification
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Gained recognition in recent decades
For much of history, purple diamonds were misclassified as pink or brown diamonds. Subtle colour differences were difficult to detect before modern grading techniques.
It was only in the late 20th century that gem laboratories began properly identifying and separating purple diamonds as their own category. This coincided with increased production from Argyle and advances in colour grading.
Today, historic purple diamonds are re-evaluated and often reclassified, adding to their prestige.
Lab-Grown Purple Diamond
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Can be created using modern technology
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Very different market value to natural stones
Lab-grown purple diamonds do exist. They are created using high-pressure high-temperature (HPHT) or chemical vapour deposition methods, with controlled lattice distortion or post-growth treatment.
While visually similar, lab-grown purple diamonds are far more affordable and lack the rarity of natural stones. They are clearly identified as laboratory-created in professional grading.
Is Purple Diamond Used in Jewellery?
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Yes, but usually in high-end or bespoke pieces
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Often set to protect and enhance colour
Purple diamonds are used in jewellery, but almost exclusively in high-end or custom designs. Their rarity means they are rarely seen in mass-market pieces.
Jewellers often set them in rose gold or platinum to enhance the colour. Protective settings are common, even though diamonds are durable, due to the stone’s value.
Many purple diamonds are bought to be worn occasionally rather than daily.
Where Else Is Purple Diamond Used?
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Collected as investment gemstones
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Studied in gemmological research
Outside jewellery, purple diamonds are primarily held in private collections or institutional vaults. Some are never set at all, remaining as loose stones.
They are also studied in gem laboratories to better understand crystal lattice distortion and colour formation in diamonds. This research benefits the wider diamond industry.
There are no industrial uses specific to purple diamonds.
Why Is Purple Diamond Studied?
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Helps explain diamond colour formation
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Provides insight into Earth’s deep processes
Purple diamonds help scientists understand how extreme stress affects crystal structures at the atomic level. This research has implications beyond gemology, including material science.
They also offer clues about tectonic movement and geological conditions deep within the Earth. Every purple diamond is, in effect, a record of immense pressure frozen in time.
For gem experts, they represent one of the most complex colour phenomena in diamonds.
Conclusion
Purple diamonds are not just rare. They are extraordinary. Their colour is born from pressure so intense it reshapes atoms, and their scarcity has only increased with time.
As a jewellery expert, I see purple diamonds as the intersection of beauty, science, and rarity. They are stones for those who value meaning as much as appearance. Whether admired in a ring, a vault, or a laboratory, purple diamonds stand among the most fascinating gems on Earth.
FAQ
Are purple diamonds natural?
Yes, natural purple diamonds exist, though they are extremely rare.
Are purple diamonds more valuable than pink diamonds?
In many cases, yes, especially when the purple colour is strong and pure.
Do purple diamonds fade over time?
No, diamond colour is stable and permanent.
How can you tell if a purple diamond is real?
Professional laboratory grading is essential to confirm authenticity and origin.
Are lab-grown purple diamonds worth buying?
They can be a good choice for jewellery, but they do not hold the same value as natural stones.