Blue diamond: a rare colour, a fascinating history
Why does the blue diamond fascinate so much?
The blue diamond is one of the rarest and most captivating gemstones in the world. Unlike other coloured diamonds, its natural blue hue comes from the presence of boron, a chemical element that integrates into the crystal structure during diamond formation. This exceptional and extremely rare geological phenomenon gives the blue diamond its deep and enchanting colour that has fascinated collectors and jewellery enthusiasts for centuries.
A unique formation in the heart of the Earth
Blue diamonds form like all diamonds: under high pressure and temperature, several hundred kilometres beneath the Earth's surface. What distinguishes them is the incorporation of boron atoms into their crystal structure during formation. This presence of boron alters how the diamond absorbs and reflects light, creating this very particular blue hue. The higher the boron content, the more intense the colour.
This natural incorporation of boron is extremely rare: it's estimated that less than 0.1% of mined diamonds display a natural blue hue. This extraordinary rarity explains why blue diamonds are among the most precious and sought-after stones in the world.
The nuances of blue: a rarity in itself
Blue diamonds come in a range of hues from pale blue to intense blue, sometimes with violet or grey undertones. On the GIA (Gemological Institute of America) scale, they're classified by intensity: Fancy Light Blue, Fancy Blue, Fancy Intense Blue, and the extremely rare Fancy Vivid Blue.
The colour can be uniform or nuanced, and the more vivid and pure the hue, the rarer and more precious the stone. Lab-grown blue diamonds now reproduce these magnificent hues, but those with 100% natural colour (certified by recognised laboratories) reach astronomical prices on the market.
The blue diamond in history: some iconic examples
Among the rare known blue diamonds, three specimens stand out for their history and exceptional rarity:
The Hope Diamond:
Undoubtedly the most famous, this 45.52-carat diamond is displayed at the Smithsonian Institution in Washington. Its deep blue colour with violet undertones and its eventful history make it a legendary stone. Originally from the Golconda mines in India, it was once known as the "Blue of France" and was part of the French Crown Jewels before being stolen during the French Revolution. Recut and renamed, it passed through several owners before being donated to the American museum by jeweller Harry Winston in 1958.
The Blue Moon of Josephine:
This 12.03-carat intense blue diamond is considered one of the most precious ever sold at auction. Discovered at the Cullinan mine in South Africa in 2014, it was sold by Sotheby's in Geneva in 2015 for the record sum of $48.4 million, or more than $4 million per carat. Purchased by a Hong Kong billionaire for his 7-year-old daughter, this diamond stands out for its exceptionally pure and vivid blue colour, classified as Fancy Vivid Blue by the GIA.
The Wittelsbach-Graff:
This historic 31.06-carat diamond dates back to the 17th century and was part of the Bavarian Crown Jewels. Acquired in 2008 by jeweller Laurence Graff for $24.3 million, it was slightly recut to improve its brilliance whilst preserving its exceptional weight. Its Fancy Deep Blue colour and royal history make it one of the most prestigious diamonds in the world.
These rare stones are admired not only for their beauty but also for the stories they carry across centuries and continents.
Evaluation criteria for a blue diamond
Valuing a blue diamond relies on several criteria:
- Hue and intensity: the deeper and more uniform, the rarer the stone
- Clarity: like all diamonds, inclusions impact value, but to a lesser extent than colour
- Carat weight: stones above 1 carat are extremely rare
- Cut: a cut that enhances the colour and maximises its expression increases value
- Natural origin: certified by an independent laboratory such as GIA or IGI
What is the value of a blue diamond?
Natural blue diamonds are among the most expensive stones in the world. A certified stone, even of small size, can reach astronomical sums. In 2016, the 14.62-carat Oppenheimer Blue was sold at Christie's for $57.5 million, setting a world record at the time for a diamond at auction. In 2015, the 12.03-carat Blue Moon of Josephine reached $48.4 million, or more than $4 million per carat, a per-carat price never matched for a diamond. The price varies according to colour intensity and the other criteria mentioned, but also according to origin: blue diamonds from the Cullinan mines in South Africa or Golconda in India are particularly prized for their exceptional quality.
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Why choose a blue diamond?
Beyond its rarity, the blue diamond carries strong symbolism: depth, serenity, wisdom. It's a stone that attracts those seeking originality and refinement. Choosing a blue diamond means opting for a touch of timeless elegance that transcends fashion.
And whilst the price of natural stones remains prohibitive for most, there's now a credible alternative: the lab-grown blue diamond. Thanks to remarkable technological advances, these laboratory-created gemstones offer a striking blue colour whilst meeting demanding ethical and aesthetic criteria. This modern and committed option represents a wise choice for those wishing to own this exceptional stone without compromising on beauty or values.
Conclusion
The blue diamond combines science, history and aesthetics. Its natural rarity, unique formation process and incomparable beauty make it an exceptionally coveted stone. Whether you're passionate about gemmology or simply looking for an original stone for an important moment in your life, the blue diamond deserves your attention. Its enchanting hue will continue to fascinate and inspire for generations to come.
