Blue Diamonds

A diamond is a natural crystalline carbon that is valued as a gem. Diamonds occur in various forms and colours. They can either occur in diamond type I or type II. Even though diamonds have been known to be colourless, they are some rare variations of the gems that come in different colours, for example, pink diamonds, blue diamonds and many more.

This article will give precise details about the blue diamonds from their formation and features to the most valuable variation of the diamonds.

What are blue diamonds?

A blue diamond is one of the type II diamonds, but the only difference is that it is blue. The visible blue colour comes from the presence of boron atoms in the mineral’s carbon crystal lattice. The boron’s molecule causes absorption of red-light wavelengths, therefore transmitting the blue light which is seen by the human’s eyes.

The blue diamonds are highly valued due to their beautiful nature and rare presence. Blue colours have also been linked with royalty and wealth, which make their demand to rise increasing their scarcity and prices.

The natural blue mines are found in fewer places which include Golconda mine in India, Cullinan mine in Pretoria, South Africa and Argyle mine in Australia.

Although blue diamonds can be formed naturally, they can also be formed artificially through a lab process. The artificial/lab-made blue diamonds are, however, less valued than the naturally occurring ones. We’ll discuss these artificial blue diamonds later on in this article.

How are blue diamonds formed?

It is believed that diamonds are formed deep down the earth’s surface, particularly from the mantle. A colourless diamond is made purely from carbon atoms. The blue colour in these gems is formed when some small amounts of boron atoms replace some carbon atoms in the diamond crystal.

The boron atom then causes a change in how light passes through the diamond crystalline. It absorbs the red-light wavelengths in the crystal’s spectrum, transmitting the blue light visible in a human’s eyes.

Current research shows that the boron materials have once been instituted in the oceanic waters. This research can explain why blue diamonds are rare. The mines where the gems are extracted were sited just above the subducted oceanic crust.

The boron materials were carried down to the earth’s mantle during the oceanic crust subduction process.

Variations of the blue diamonds

The blue diamonds can be naturally formed in different variations of the blue colour. The concentrated blue diamonds are the most valuable. They are formed when a large amount of the boron atoms substitutes the carbon atoms in the diamond crystalline. The more the boron atoms present in the diamond, the more the blue colour becomes concentrated. 

The rich-blue diamonds are scarce and hence very expensive. The prices increase as the intensity of the blue colour increases. Of course, the price will also increase as the size of the gem increase. This means that a large-sized deep blue diamond will cost a fortune.

Other blue diamonds can come with a mixture of other different colours, for example, the greyish blue diamonds, greenish-blue diamonds, intense violetish blue diamonds and many more. These other colours are formed when small amounts of nitrogen in the diamond crystalline reduce the effect of the boron atoms.

This reduces the absorption impact of the red light in a diamond, thus reducing the blue wavelength transmission giving room for other colours also to be transmitted.

Other blue colour diamond variations include light grey-blue diamonds, deep-green blue diamonds, vivid greenish-blue diamonds, fancy greyish greenish blue diamonds and many others. You can always research on other variations and their features.

Artificial/ Lab-made blue diamonds

Blue diamonds are always attractive, displaying a sign of wealth and royalty. This has increased their demand hence increased their scarcity. To counter this problem, scientists have come up with a way of increasing the supply of these gems. 

They change the diamonds with less valuable colours to blue-coloured ones. Does it sound confusing? Well to make it simpler, they expose the diamonds with less valuable colours to radiation, high temperatures and high pressure to produce the blue colour.

The blue colour can also be formed during the coating process. This process occurs when thin blue material is applied on the surface of a diamond with another colour. The coating is often less durable than the diamond itself; hence it will wear out over time, leaving the original colour exposed.

These artificial diamonds are less valuable than natural ones. Imposters have conned some people by selling artificial blue diamonds with the same price as the natural ones. Customers buy them thinking that they are ”original”.

To prevent this situation from happening to you, there are some signs you must look for to differentiate between the two blue diamonds. First, natural blue diamonds can conduct electricity. The boron material present gives it the ability to conduct electrical power.

Secondly, artificial blue diamonds tend to wear our faster, especially coated ones. However, this method may not be that sufficient since it requires a more extended period to confirm it. A customer can always use the first method to confirm. 

Top 4 well-known blue diamonds

Some of the famous blue gems that are owned or have been sold include:

1. The Okavango blue diamond

This is a 20.46 carat diamond with a Fancy Deep blue colour and a VVS clarity. 

2. The Hope diamonds

The Hope diamond is a 45.55 carat diamond with Fancy Dark Grayish blue colour owned by the Smithsonian company. It has an estimated value of around $200 million.

3. The Wittelsbach diamond

This 35.56 carat diamond with greyish-blue colour has a long history of possession. The gem was first owned by King’s Philip IV daughter, Margaret Teresa and later passed a long series of possession until it was sold to Laurence Graff at $23.4 million. Graff reformed the gem, improving its features and later sold it for around $80 million. 

4. Blue Moon of Josephine

The 12.03-carat diamond has a Fancy vivid blue colour. It has the widely-known reputation of being the most expensive diamond ever sold at auction at a whopping $48.4 million. A billionaire bought it from Hong Kong who gave it to his daughter, Josephine as a present and hence deriving its name.


Coloured diamonds have been known to be rare and valuable. One of the coloured diamonds is blue diamonds. Just like the Australian pink diamonds and investment diamonds, these diamonds are highly valued.

Getting to know their features will not only help when buying them but also help you differentiate between the natural ones and the lab-made ones.