Blue diamonds: Properties, characteristics and uses

In the depths of the planet, the most precious gems in the world, blue diamonds, are formed. These enigmatic stones have a complex geological description, as well as being very valuable and rare.

The National Museum of Natural History in Washington, DC exhibits the most famous example of the Hope Diamond, in a sophisticated and deep blue-gray. As shown in the following image:

Characteristic

Are blue diamonds because the color of his body is blue. Finding this gem naturally is difficult, generally the mineral inclusions it presents are scarce. These characteristics and its great clarity give it its high value.

Few mines in the world produce blue diamonds, and they do it in small quantities. The bluish coloration is due to small portions of boron, on the crystal lattice. This blue jewel can also be created artificially in laboratories, and with natural diamond treatments.

Why are they blue?

When a diamond has only carbon atoms in its structure, it will be considered pure, without defects, and will be colorless. When alterations occur in the crystal lattice, colored diamonds appear. Among the alterations that occur are the replacement of carbon atoms, and the presence of non-diamond mineral particles embedded in the diamond.

The blue coloration is often produced when a small amount of boron replaces carbon atoms in the crystal lattice. The occurrence of these events is paradoxical, since boron is rarely found in the remote environment of the Earth, where natural diamonds are generated.

A small concentration of boron is enough to generate the blue color of the diamond, as the concentration increases the blue color will be more intense.

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Boron can enter the diamond lattice, due to its small size, and replace a carbon atom (as shown in the image). However, it has one fewer electron, in relation to carbon, this translates into a deficiency of electrons, causing alterations in the crystalline structure of the diamond.

This alteration affects the passage of light through the diamond. When light falls on the diamond, it causes it to absorb the red fraction, and transmit the blue fraction. When the transmitted light reaches the human eye, the blue diamond is observed.

Boron substitution in diamond: It happens that when boron atoms replace carbon atoms in the crystal lattice of the diamond, it causes the mineral to selectively absorb the red wavelengths of light and selectively transmit the blue color and therefore are the wavelengths blue those that reach the viewer.

How are they formed?

For many years geologists believed that diamonds found on the surface were created with elements from the Earth’s surface layer 100 to 150 kilometers away.

The finding of a group of researchers in 2018 was surprising, when obtaining a number of blue diamonds formed at pressures corresponding to a very deep layer of the Earth, approximately 410 to 660 kilometers. These also had inclusions, whose origin could only be from materials from the oceanic lining.

These discoveries clarified why the blue diamonds They are only found in small quantities in the mines. The location of those mines was on a slab of subducted oceanic crust, pushing boron into the depths.

Later, thanks to volcanic eruptions, the elements present at that depth rose to the earth’s surface.

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Famous blue diamonds

Between the blue diamonds best known worldwide are:

Diamond Hope

The Hope Diamond, an ancient jewel dating from 1653. It belongs to the Smithsonian Institution, and is the main attraction of the gem exhibition. It is the most famous gemstone worldwide, valued between 200 and 250 million dollars. In the following photo you can see a replica of the Hope Diamond:

Diamond Wittelsbach

The historical value of the Wittelsbach diamond made it attractive to many, with its luxurious blue-gray coloration. Laurence Graff bought this gem and had its virtues improved, increasing its value, greater than 80 million dollars. A replica of this jewel can be seen in the image:

Okavango Blue Diamond

First unveiled in April 2019, the “Okavango Blue” a 20-carat diamond owned by the Botswana government.

Josephine’s Blue Moon

12 karat cushion shaped gemstone with Fancy Vivid blue tint. Sold during 2015 in a Sotheby’s sale in Hong Kong for $48.4 million.

How much do blue diamonds cost?

The most valuable diamonds are natural diamonds with an even distribution of pure blue color in the body of the gem. Being rare, their sale price can exceed a million dollars per carat. Below are the prices of some diamonds, according to recent auctions.

The blue diamonds natural, they are altered acquiring a green or gray secondary hue. Blue-green and blue-gray diamonds are rare, and like natural blue gems with a faint hue, they are sold for lower prices.

Blue diamonds sold at auction   
NamePolished Carat WeightColorPrice
Oppenheimer Blue14.62elegant vivid blue$57,231,903
josephine blue moon12.03elegant vivid blue$48,468,158
Memory of Autumn Leaves (Apollo)14.54elegant vivid blue$42,087,302
the diamond zoe9.75elegant vivid blue$32,645,000
De Beers Millennium Jewel 410.1elegant vivid blue$32,013,223
The blue13.22elegant vivid blue$24,202,829
The diamond blue sky8.01elegant vivid blue$17,074,168
Bvlgari blue10.95elegant vivid blue$15,762,500
the diamond there5.0elegant vivid blue$13,873,082
blue diamond ring13.39deluxe deep blue$9,288,823
The Farnese Blue6.16dark blue gray fantasy$6,713,837
blue diamond ring3.47deluxe deep blue$6,663,300
ring etc3.37deluxe deep blue$2,770,856
green-blue diamond ring1.11Fancy Vivid green-blue$415,111
blue and colored diamond ring2.11elegant vivid blue$379,393
teal pearl and diamond ring1.62Fancy Vivid Teal$350,880
blue diamond ring0.87elegant blue$231,203

Lab-Made Blue Diamonds

Many people want to show off blue diamonds, which is why ways of treating them and producing the blue color have emerged. Irradiation, treatments with high temperatures and pressure, coating with colored material on the surface of the gem, are used with the aim of producing the blue color in the jewel.

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Cultured diamonds are made by incorporating boron into the culture. These diamonds are quite common and are offered at lower prices, offering an equally attractive alternative for a public that cannot afford genuine diamonds.

Blue diamond producing mines

Few mines form blue diamonds, and the most famous have been discovered in three places:

  • Mines in India. Located in Golconda Sultanate, India. The most famous jewels Hope Diamond and Diamon Wittelsbash-Graff were found in these mines. The table below shows a list of the blue diamonds from Golconda.
  • South African mines. Known as the Culligan mine, the world’s most important diamond generator. Produces blue diamonds larger rough, and a valuable portion of heavyweight diamonds. It currently belongs to Petra Diamonds. The following table lists the blue diamonds most important of the Cullinan mine.
  • Western Australian mines. The Argyle mine generates the largest volume of diamonds in the world. Although the production of blue diamonds is minimal, for 2009 they offered a collection of diamonds between blue and purple accumulated over several years.
Major Blue Diamonds from Golconda, India  
NamePolished Carat WeightColor
idol eye70.21elegant light blue
the diamond of hope45.52Dark Blue-Grey Fantasy
Mouawad Blue42.92elegant blue
Crown of Charlemagne37.05elegant light blue
sultan of morocco35.27whimsical blue-gray
Wittelsbach Graff31.06elegant deep blue
Brunswick Blue13.75elegant blue
Major blue diamonds from the Cullinan mine  
NamePolished Carat WeightColor
the blue heart30.62elegant deep blue
blue lily30.06deluxe deep blue
the heart of eternity27.64elegant vivid blue
transvaal blue25.00elegant blue
Sam Abram Fancy Blue20.17elegant vivid blue
Graff Blue Ice Diamond20.02elegant deep blue
Oppenheimer’s Blue14.62elegant vivid blue
the blue empress2:00 p.m.elegant blue
The Begum Blue13.78elegant deep blue
The blue13.22elegant vivid blue
blue magic12.02elegant vivid blue

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