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Ultimate guide to

Fancy Blue Diamonds

What are Blue Diamonds?

As blue is one of the rarest occurring colours in nature, it is also one of the most desired natural coloured diamond hues. Blue diamonds are among the least common colours of fancy coloured diamonds, which themselves make for only 0.01% of all extracted diamonds. Blue brilliants are characterized by their high clarity, which, combined with their rarity, puts them in the top most expensive coloured diamonds.


These diamonds, however, are not only rare but also extremely desirable. Blue colour is considered the most beautiful by majority of society. It is not surprising, given that it is known for its calming and nurturing effects. For that reason, it might be the perfect choice, presenting it as an engagement ring to a loved one.


The origin of Blue Diamonds

Blue diamonds owe their colour to the presence of boron molecules in the diamond’s crystal lattice. This phenomenon, however, is incredibly rare because of the fact that boron is not usually found on such deep levels in the Earth, where natural diamonds are formed. For the blue shade to be visible in a diamond, only a small amount of boron, such as 1 in a million particles, is enough. The higher the ration of boron to carbon elements, the more intense the colour will be.

Because of their appearance, they may sometimes be confused with sapphires, which belong to completely different family of gemstones. Sapphire is a blue variant of corundum, the second hardest mineral after a diamond. Despite their similar appearance, their price differs significantly.

There are only a few mines around the world where blue diamonds are mined. These include the Cullinan mine in South Africa and Golconda mine in India. Previously, this also included the Argyle mine in Australia, however, it was closed in 2020.

Colour intensity of Blue diamonds

Blue diamond
Diamonds are graded based on many factors that classify their value. In the case of colourless diamonds, the 4C method is responsible for their evaluation, about which more information can be found in The 4Cs of Diamonds article. However, when it comes to coloured diamonds, one of the factors is hue intensity. It describes the expressiveness and saturation of a diamond’s hue. The scale below shows the intensity levels of blue diamonds.

Fancy blue diamond hue intensity scale:

• Faint Blue
• Very Light Blue
• Light Blue
• Fancy Light Blue
• Fancy Blue
• Fancy Intense Blue
• Fancy Vivid Blue
• Fancy Deep Blue
• Fancy Dark Blue

Blue diamonds appear in hues ranging from Faint to Fancy Dark. As with other coloured diamonds, the more saturated the colour is, the greater its value is. It is related to the frequency of occurrence of a given colour with a specific saturation. The least common hue intensity is Fancy Vivid, which is also the most expressive and the most desirable. However, the most common hue intensities are the most delicate ones, such as Faint, Very Light and Light. The differences are visible not only in the colour of a diamond, but also in price. A blue diamond of highly saturated colour will be valued at a higher price than a blue diamond of almost white colour. 

Blue diamonds prices

Average wholesale prices of blue diamonds with good specifications start from about $ 40,000* per carat and end at about $ 375,000* per carat. Blue brilliants belong then to one of the most expensive fancy coloured diamonds in the world. The reason for that is the fact, that they are one of the least common coloured diamonds. They are second most valuable diamonds after red diamonds. 

Average blue diamonds price ranges with the specifications:

•    Clarity: VS
•    Shape: Cushion
•    Cut: Good
•    Polish/symmetry: Very good
•    Complementary hue: None
•    Fluorescence: None

Blue diamonds prices
All prices are per 1 carat – to get an actual diamond’s price, multiply the given price by the carat weight

As it is shown in the table above, the price of blue diamonds reaches very high amounts. For comparison, a pink diamond of 1 Ct weight and Fancy Pink colour is estimated at a price ranging from $ 97,000 per carat to $ 177,000 per carat. It is then about 60% of a blue diamonds price of the same specifications. Such differences are incredible, especially considering the fact that pink diamonds are the third most expensive diamonds, after blue diamonds. 

*price refers to a diamond of 0.50 Ct weight, VS clarity, no complementary hues, cushion shape, good cut/polish/symmetry, and no fluorescence

Appreciation of Blue diamonds over the years

Natural blue diamonds are one of the most valuable diamonds on the Fancy Coloured Diamonds market. It is not surprising that their prices are increasing year by year, setting new price records. Due to their high value, they are an exceptionally luxurious good, accessible only to a small group of people. Let us see how their popularity has changed over the years.
Chart of blue diamond appreciation

Source: The Fancy Colour Research Foundation


As it is shown in the chart above, the popularity of blue diamonds grew significantly in the years 2005-2020. Fancy Vivid Blue diamonds enjoyed the greatest recognition in this period of 382.2%, a bit further, but also highly popular were Fancy Intense Blue diamonds (317.6%), followed by Fancy Blue diamonds of 287.9% recognition. For comparison, the appreciation of yellow diamonds during this period was around 50%. This shows how much interest there is for blue diamonds, and based on the chart above, we can predict a further increase in appreciation, and hence – higher prices.

Complementary hues of Blue diamonds

Another important factor in assessing the value of coloured diamonds, in addition to the colour intensity, is the hue complementary to the main hue. Depending on the value of a dominant hue, the complementary hue may lower the price - in the case of precious coloured diamonds, or increase the price - in the case of less valuable coloured diamonds. The most valuable of them with complementary hues can only get decreased in price. Thus, the most valuable Fancy Coloured diamonds would have the highest prices in the form of pure singular shade.

The number of complementary hues in a diamond also affects the value of the diamond. The more there is of them, the lower the price will be. Typically, diamonds have one or two complementary hues. Their name is constructed in such a way that the dominant colour is placed at the end of the name, and additional colours are placed successively in front of the main diamond colour. For example, a grey-blue coloured diamond would be called Fancy Gray Blue.

As blue diamonds are one of the most valuable colours of diamonds, their price goes down if there is a complementary hue. Blue diamonds are most often mixed with grey (Grey/Greyish). The less common complementary hue is green (Green/Greenish), and the rarest - violet (Violet/Violetish). The grey hue, as it is most often found in the company of blue, has the greatest impact on lowering the price of a diamond. The visibility of a green shade will also result in a lower price for a blue diamond. Only the violet colour, which is also very rare, will increase the value of a blue diamond.

Famous Natural Blue Diamonds

Embed from Getty Images
•    The Hope Diamond
This diamond is one of the most popular diamonds, if not the most popular in the world. It reaches carat weight of 45.52 Ct, and its history dates back to the 17th century in India, where it was mined from the Kollur Mine. Thanks to its extraordinary size, previously unknown information about diamond formation was discovered. However, it is quite a controversial diamond, because when it was purchased by Evalyn Walsh McLean in 1912, a series of tragic events went through her life, which was attributed to this diamond. Many people still believe in the curse of this beautiful diamond.

•    The Oppenheimer Blue Diamond
This unusual diamond weighs 14.62 Ct and its color is classified as Fancy Vivid. In 2016, it was given the title of the most expensive diamond sold at an auction and held that title for the next year. Its price was then an extraordinary 57.5 million dollars.

•    The Wittelsbach-Graff Diamond
This diamond weighs 31.06 Ct, while its colour has been graded as Fancy Deep Blue of IF clarity. It comes from the Kollur Mine in India, where it was mined in the 17th century. Then in 2008, it was bought by Laurence Graff who renamed it from Wittelsbach Diamond to Wittelsbach-Graff Diamond. After this transaction, it was repolished, which is now considered by many critics a bad decision due to the loss of its character and history.

•    The Heart of Eternity Diamond
This unique diamond has an extraordinary Fancy Vivid Blue colour and weighs 27.64 Ct. As the name "Heart of Eternity" indicates, its shape represents a heart. At the time of extraction, the rough diamond weighed 777 Ct, and then a decision was made to divide it into parts, one of which is this diamond. Its estimated value is over 16 million dollars.

•    The Blue Heart Diamond
This heart-shaped blue diamond originates from the Premier Mine in South Africa, where it was discovered in 1908. Two years later, it was cut from a stone weighing 100.5 Ct to a stone weighing 30.62 Ct. It owes its popularity to the Fancy Deep Blue colour and a heart-shaped cut, making it one of the most beautiful diamonds in the world.

•    The Blue Moon of Josephine Diamond
It was discovered in 2014 in the Cullinan Mine in South Africa, where it reached a weight of 29.62 Ct. It was then cut into a cushion shape, resulting in a weight reduction to 12.03 Ct. Its colour is graded as Fancy Vivid Blue of IF clarity, making it extremely rare. It was sold in the same year for a record price of 48.4 million dollars. Originally its name was The Blue Moon, however, redeemed by a Hong Kong billionaire, it was renamed in honour of his 7-year-old daughter, Josephine.
Fancy Yellow Diamond ring in black gold

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