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Diamonds have long been associated with luxury, rarity and exceptional craftsmanship, but some diamonds have reached extraordinary prices that go far beyond traditional jewellery.
From vivid pink diamonds to rare blue and orange stones, the world’s most valuable diamonds are prized for an exceptional combination of colour, clarity, carat weight, cut and rarity.
At auction, some of these extraordinary gemstones have sold for more than AUD$99 million.
So, what is the most expensive diamond in the world? And what makes these diamonds so valuable?
Here at Diamondport Jewellers, we’ve researched some of the most significant publicly recorded diamond auction sales to bring you the top 10 most expensive diamonds ever sold at auction.
Note: This list ranks diamonds according to publicly documented auction sale prices. The original auction prices were recorded in US dollars. The Australian dollar figures in this article are approximate conversions using an exchange rate of approximately USD$1 = AUD$1.40 and may change over time.
| Rank | Diamond | Carat Weight | Colour | Approx. Auction Price (AUD) |
| 1 | CTF Pink Star | 59.60 ct | Fancy Vivid Pink | A$99.3 million |
| 2 | Williamson Pink Star | 11.15 ct | Fancy Vivid Pink | A$80.5 million |
| 3 | Oppenheimer Blue | 14.62 ct | Fancy Vivid Blue | A$80.3 million |
| 4 | De Beers Blue | 15.10 ct | Fancy Vivid Blue | A$80.2 million |
| 5 | Pink Legacy | 18.96 ct | Fancy Vivid Pink | A$70.3 million |
| 6 | Blue Moon of Josephine | 12.03 ct | Fancy Vivid Blue | A$67.7 million |
| 7 | Graff Pink | 24.78 ct | Fancy Intense Pink | A$64.5 million |
| 8 | The Orange | 14.82 ct | Fancy Vivid Orange | A$49.6 million |
| 9 | The Zoe Diamond | 9.75 ct | Fancy Vivid Blue | A$45.5 million |
| 10 | The Unique Pink | 15.38 ct | Fancy Vivid Pink | A$44.1 million |
The original auction prices and records are documented by major auction houses and diamond industry sources.
The CTF Pink Star holds the record for the most expensive diamond ever sold at auction.
This remarkable 59.60-carat Fancy Vivid Pink diamond sold for USD$71.2 million, equivalent to approximately AUD$99.3 million, at Sotheby’s Hong Kong in 2017.
It was renamed the CTF Pink Star after its purchase by Hong Kong jeweller Chow Tai Fook.
The diamond began life as a much larger 132.5-carat rough diamond discovered in Africa in 1999. It took approximately two years of cutting and polishing to transform the rough stone into the finished oval-shaped diamond.
The CTF Pink Star is particularly exceptional because it combines significant size with an extraordinary level of colour and clarity.
The GIA graded it Fancy Vivid Pink and Internally Flawless, making it the largest Internally Flawless Fancy Vivid Pink diamond the laboratory had graded.
Its sale remains the highest publicly recorded auction price for a diamond or gemstone.
The CTF Pink Star demonstrates why rare coloured diamonds can command extraordinary prices. Its value comes from the combination of:
59.60-carat weight
Fancy Vivid Pink colour
Internally Flawless clarity
Exceptional colour saturation
Natural colour
Extraordinary rarity
The Williamson Pink Star is another extraordinary pink diamond, weighing 11.15 carats.
Graded Fancy Vivid Pink and Internally Flawless, it sold for USD$57.7 million, equivalent to approximately AUD$80.5 million, at Sotheby’s Hong Kong in 2022.
The diamond was cut from a 32-carat rough stone discovered at the Williamson Mine in Tanzania.
Its sale achieved approximately USD$5.18 million per carat, making it one of the most expensive diamonds ever sold on a price-per-carat basis.
Its name also connects it to another famous diamond: the Williamson diamond presented to Queen Elizabeth II as a wedding gift in 1947.
The Williamson Pink Star is a perfect example of how colour intensity and rarity can sometimes have an even greater influence on value than carat weight alone.
The Oppenheimer Blue is one of the most famous blue diamonds ever sold.
Weighing 14.62 carats, the rectangular step-cut diamond was graded Fancy Vivid Blue and sold for USD$57.54 million, equivalent to approximately AUD$80.3 million, at Christie’s Geneva in 2016.
The diamond was named after Sir Philip Oppenheimer, a prominent figure in the diamond industry and a former owner of the stone.
At the time of its sale, the Oppenheimer Blue became the most expensive gemstone ever sold at auction, surpassing the previous record held by another famous coloured diamond.
Blue diamonds are exceptionally rare because their colour is generally associated with trace amounts of boron within the diamond’s crystal structure.
The De Beers Blue, sometimes referred to as the De Beers Cullinan Blue, is a spectacular 15.10-carat Fancy Vivid Blue diamond.
It sold for USD$57.47 million, equivalent to approximately AUD$80.2 million, at Sotheby’s Hong Kong in 2022.
The step-cut diamond was discovered at the famous Cullinan Mine in South Africa in 2021. It was graded Fancy Vivid Blue and Internally Flawless by the GIA.
Its 15.10-carat size also made it the largest Fancy Vivid Blue diamond ever offered at auction at the time of its sale.
The result was particularly impressive because it came within a fraction of the record set by the Oppenheimer Blue six years earlier.
The Pink Legacy is an 18.96-carat Fancy Vivid Pink diamond that sold for USD$50.4 million, equivalent to approximately AUD$70.3 million, at Christie’s Geneva in 2018.
The diamond was originally associated with the Oppenheimer family and was later purchased by Harry Winston. Following its acquisition, it was renamed the Winston Pink Legacy.
Its exceptional colour, clarity and size made it one of the most important pink diamonds ever offered at auction.
The Pink Legacy demonstrates an important point about coloured diamonds: a stone does not necessarily need to be the largest diamond in existence to achieve an extraordinary price. Colour quality and rarity can dramatically increase a diamond’s value.
The Blue Moon of Josephine is a 12.03-carat Fancy Vivid Blue diamond that sold for USD$48.5 million, equivalent to approximately AUD$67.7 million, at Sotheby’s Geneva in 2015.
Before the sale, the diamond was known simply as the Blue Moon. After being purchased by a private collector, it was renamed the Blue Moon of Josephine.
The cushion-shaped diamond is Internally Flawless and was discovered at the Cullinan Mine in South Africa as a 29.62-carat rough diamond.
Its auction result was particularly significant because it established a record price of more than USD$4 million per carat, making it one of the most valuable diamonds ever sold on a price-per-carat basis.
The Graff Pink is one of the most famous pink diamonds in the world.
This 24.78-carat Fancy Intense Pink diamond sold for USD$46.2 million, equivalent to approximately AUD$64.5 million, at Sotheby’s Geneva in 2010.
Before its auction, the diamond had reportedly been owned by legendary jeweller Harry Winston. It was later purchased by Laurence Graff, who renamed it the Graff Pink.
Its emerald-style step cut is particularly striking because this type of cut is traditionally associated with colourless diamonds. In a rare pink diamond, the combination creates an especially distinctive appearance.
At the time of its sale, the Graff Pink set a world auction record for a pink diamond.
Not all of the world’s most expensive diamonds are pink or blue.
The Orange is an extraordinary 14.82-carat Fancy Vivid Orange diamond that sold for USD$35.5 million, equivalent to approximately AUD$49.6 million, at Christie’s Geneva in 2013.
The pear-shaped diamond was the largest Fancy Vivid Orange diamond ever offered at auction at the time and established a world auction record for an orange diamond.
Its sale price also reached approximately USD$2.4 million per carat, demonstrating just how valuable exceptionally rare natural colour can be.
Pure orange diamonds are extremely rare, particularly at larger sizes, making The Orange one of the most significant coloured diamonds ever brought to auction.
The Zoe Diamond, formerly known as the Mellon Blue, is a 9.75-carat Fancy Vivid Blue diamond.
It sold for USD$32.6 million, equivalent to approximately AUD$45.5 million, at Sotheby’s New York in 2014.
The pear-shaped blue diamond was originally part of the collection of American philanthropist and art collector Rachel Lambert Mellon.
Its auction price was more than double the high estimate, demonstrating the intense demand for exceptional blue diamonds among collectors.
Rounding out our list is The Unique Pink, a 15.38-carat Fancy Vivid Pink diamond.
The diamond sold for USD$31.6 million, equivalent to approximately AUD$44.1 million, at Sotheby’s Geneva in 2016.
The diamond is notable for its exceptional colour saturation and rarity.
Its combination of size, colour and quality helped make it one of the most significant pink diamonds to appear at auction.
The Unique Pink’s sale illustrates how a combination of colour, size, clarity and diamond type can make a stone exceptionally desirable to collectors.
Looking at the world’s most expensive diamonds, one thing becomes immediately clear: rare coloured diamonds dominate the list.
Pink and blue diamonds appear repeatedly because naturally occurring diamonds with strong, desirable colour are exceptionally rare.
For fancy coloured diamonds, colour is assessed differently from the traditional D-to-Z colour scale used for most colourless diamonds.
Stones can receive grades such as Fancy, Fancy Intense, Fancy Vivid, Fancy Deep and Fancy Dark, depending on their colour characteristics.
The most desirable stones can combine intense colour with excellent clarity and significant carat weight.
Pink diamonds are particularly rare. The Argyle Mine in Western Australia was historically responsible for the majority of the world’s pink diamond supply before closing in 2020. The closure significantly reduced the availability of new Argyle pink diamonds.
Blue diamonds are also incredibly rare.
Their blue colour is associated with boron within the diamond’s crystal structure, making naturally occurring blue diamonds a geological rarity.
When discussing the most expensive diamonds in the world, it is important to distinguish between diamonds that have been publicly sold and famous diamonds whose value is essentially impossible to establish.
The Hope Diamond, for example, is one of the world’s most famous gemstones.
Weighing 45.52 carats, it is a Fancy Deep greyish-blue diamond and is currently held by the Smithsonian Institution.
Because it is not regularly traded on the open market, there is no verified auction sale price that can be used to rank it alongside diamonds such as the CTF Pink Star.
The Cullinan Diamond is even more remarkable from a historical perspective.
The original rough diamond weighed an extraordinary 3,106 carats, making it the largest gem-quality rough diamond ever discovered.
It was eventually cut into several major stones, including the Cullinan I and Cullinan II, which form part of the British Crown Jewels.
These diamonds are invaluable pieces of history, but assigning them a precise market value would be speculative.
The world’s most expensive diamonds are more than valuable gemstones. They are geological rarities, works of craftsmanship and pieces of history.
From the record-breaking CTF Pink Star, worth approximately A$99.3 million, to the intensely blue Oppenheimer Blue and the remarkable De Beers Blue, these diamonds demonstrate the extraordinary premiums that can be achieved when colour, clarity, size and rarity come together.
And while most people aren’t shopping for a $99 million diamond, the same principles can help you understand what makes any diamond special, and ultimately choose a stone that feels uniquely yours.
At Diamondport Jewellers, we believe choosing a diamond should be about more than simply finding the biggest stone.
It’s about understanding the qualities that matter to you and finding a diamond that balances beauty, quality and value.
Whether you’re looking for an engagement ring, wedding band or a timeless piece of diamond jewellery, our Brisbane team can help you find the right diamond for your story.
