Quick answer: The Pink Star holds the record as the most expensive diamond ever sold at auction, fetching 71.2 million US dollars at Sotheby’s Hong Kong in 2017. Other famous diamonds, including the Hope Diamond and the Cullinan I, are valued even higher but have never gone to public auction. Value comes from a combination of carat weight, colour, clarity, cut and provenance, with historic ownership and rarity of colour often mattering as much as size.
Some diamonds transcend jewellery entirely and become historical objects in their own right. Their value is not just measured by the four Cs used for a typical engagement ring, but by rarity of colour, documented history, and who owned them before they reached a museum case or a private collection. This list looks at the diamonds that have set records at auction or carry values so significant they rank among the most valuable objects on earth.
1. The Pink Star: 71.2 Million US Dollars
The Pink Star is a 59.60 carat fancy vivid pink diamond and holds the record for the most expensive diamond, and the most expensive jewel of any kind, ever sold at a public auction. It sold at Sotheby’s Hong Kong in April 2017 for 71.2 million US dollars. Mined by De Beers in Africa in 1999 as a 132.5 carat rough stone, it took a team of specialist cutters twenty months to shape it into its final oval form. The Gemological Institute of America (GIA) graded it internally flawless, the highest clarity grade possible, making it one of the purest large pink diamonds ever certified.
2. The Hope Diamond: Estimated 250 to 350 Million US Dollars
The Hope Diamond is a 45.52 carat deep blue diamond with a documented history stretching back to seventeenth century India. Its journey includes French royal ownership, a theft during the French Revolution, and a series of private collectors before jeweller Harry Winston donated it to the Smithsonian’s National Museum of Natural History in Washington DC in 1958, where it remains on public display. Because it has never returned to auction, its value is an estimate rather than a confirmed sale price, but experts place it well above the Pink Star given its size, colour and unmatched historical significance.
3. The Cullinan I: Estimated Over 400 Million US Dollars
The Cullinan diamond, discovered in South Africa in 1905, remains the largest gem quality rough diamond ever found at 3,106.75 carats. It was cut into several stones, the largest being the pear shaped Cullinan I, also known as the Great Star of Africa, at 530.2 carats. It is set in the Sovereign’s Sceptre with Cross, part of the British Crown Jewels, and has never been sold, which makes its estimated value a matter of expert appraisal rather than an auction record.
4. The Williamson Pink Star: 57.7 Million US Dollars
This 11.15 carat cushion cut fancy vivid pink diamond sold at Sotheby’s Hong Kong in October 2022 for 57.7 million US dollars, setting a world record price per carat for any gemstone at auction. Mined at the Williamson mine in Tanzania, after which it is named, it is classified internally flawless and represents one of the most concentrated expressions of value per carat in the diamond world.
5. The Oppenheimer Blue: 57.5 Million US Dollars
A 14.62 carat fancy vivid blue diamond, the Oppenheimer Blue takes its name from Sir Philip Oppenheimer, a member of the family long associated with De Beers. It sold at Christie’s Geneva in 2016 for 57.5 million US dollars and remains one of the most significant blue diamonds ever to appear at auction, prized for its exceptional colour saturation.
What Actually Drives a Diamond’s Value?
| Factor | Why It Matters |
|---|---|
| Carat weight | Larger stones are exponentially rarer, so price per carat rises sharply with size |
| Colour | Vivid, saturated fancy colours such as pink, blue and red are far rarer than colourless diamonds and often more valuable |
| Clarity | Internally flawless stones, with no inclusions visible under magnification, command the highest prices |
| Cut | A skilled cut maximises brilliance and can take months or years for exceptional rough stones |
| Provenance | Documented royal, historical or celebrity ownership can add significant value beyond the stone’s physical qualities |
Auction Records vs Estimated Values
It is worth noting the difference between a confirmed auction price and an estimated valuation. The Pink Star’s 71.2 million dollar price is a matter of public record from its 2017 sale. By contrast, figures for the Hope Diamond and the Cullinan I are expert estimates, since neither has been sold publicly in living memory. Both types of figure are commonly reported together in most rankings, but only auction results represent a price someone has actually paid.
Frequently Asked Questions
What is the most expensive diamond ever sold at auction?
The Pink Star, a 59.60 carat fancy vivid pink diamond, holds this record, selling for 71.2 million US dollars at Sotheby’s Hong Kong in 2017.
Is the Hope Diamond worth more than the Pink Star?
Experts estimate the Hope Diamond’s value considerably higher, but since it has never gone to public auction, that figure remains an estimate rather than a confirmed sale price.
Why are pink and blue diamonds worth more than white diamonds?
Fancy colour diamonds in vivid pink, blue, green and red are dramatically rarer in nature than colourless diamonds, and rarity is the primary driver of value once a stone reaches a certain size and clarity.
Where can I see the Hope Diamond in person?
It is on permanent public display at the Smithsonian’s National Museum of Natural History in Washington DC, where it has been since 1958.
What makes a diamond internally flawless?
Internally flawless is the highest clarity grade below flawless, meaning no inclusions are visible under ten times magnification, even though minor surface characteristics may exist.
Final Thoughts
The world’s most valuable diamonds share a combination of exceptional size, rare colour, and often centuries of documented history. Most people will never buy or see one of these stones in person, but understanding what drives their value helps make sense of why diamonds vary so dramatically in price. If you are researching diamonds for a purchase closer to everyday reality, our guide on choosing the perfect diamond engagement ring covers the four Cs in practical detail, and our coloured diamond jewellery guide explains how fancy colour grading works for pieces you can actually buy.