The Jewelry Box Blog

What is a Blue Diamond?

Blue diamond ring close up

If you’re the lucky owner of a natural, fancy color diamond, then you’re in possession of truly one of the rarest gemstones in the world. But if you’re not familiar with what fancy color diamonds are, especially blue diamonds, you’re about to learn some fascinating facts about this incredible gemstone. 


A Colorful Background 

As you may already know, natural diamonds were formed out of compressed carbon billions of years ago, deep underneath the surface of the earth. It’s incredibly rare for a diamond to have been formed without absorbing any chemical impurities around them, i.e. ‘flawless’ diamonds. These ‘impurities’ are what make up two of the Four C’s of Diamonds: clarity and color. Clarity is the term for the tiny little imperfections that can sometimes be found in a diamond’s internal structure, more commonly called inclusions. And color is in reference to the diamond's overall coloring. When jewelers refer to the color of a diamond, they’re referring to how white or yellow a stone appears to the naked eye. Diamonds are graded on a scale of D - Z, with D being the grade for those with no color (nearly perfect) and Z being the grade for stones with the most yellow color.

But there’s another color scale for diamonds and that scale is known as the Fancy Color Diamond Scale. These diamonds fall beyond the Z on the color scale for diamonds. Now this is where things get interesting, and Mother Nature gets the opportunity to show off her true range of talents. This color scale refers to diamonds that were turned a completely different color while they were being formed and the array shades are simply dazzling


What is a Blue Diamond? 

In the case of blue diamonds, the chemical boron is what turns the diamond blue. Blue diamonds are also mined at a depth of more than 400 feet into the surface of the earth, which is much deeper than standard diamonds. 

A faint blue diamond has tiny amounts of boron in its chemical composition and a fancy deep blue diamond contains a lot of boron. How deeply blue the diamond is colored also determines its value in the marketplace. Diamonds with deep shades of blue are much more valuable than those with a faint blue coloring because those are the rarest color blue diamonds of all. If you’re lucky enough to own any shade of natural blue diamond or really any fancy color diamond, you might want to think about insuring it if you haven’t already.


Are Blue Diamonds Real? 

Naturally mined blue diamonds are very real—and extremely expensive. However, blue diamonds that were created in a lab or artificially colored blue may cost less than what naturally mined blue diamonds do. Now you can have a naturally mined colorless diamond and then color it blue, but it too, may cost less than what a naturally mined blue diamond is worth. 


What are Color Treated Blue Diamonds? 

Color treated blue diamonds are mined diamonds that have been chemically altered in a lab. To turn the diamond blue, the diamond is irradiated with high-energy electrons in the blue wavelength range. Color treated blue diamonds aren’t considered rare and may not command the extremely high price per carat that natural blue diamonds do because they’ve been chemically altered and their certificate, should they even come with one, will say as such. 

In fact, most diamonds are color treated to hide some other imperfection that made them unappealing to potential buyers in the first place. The stone may have had an ugly hue or visible inclusion and to move the product, the wholesaler might have thought they’d have better luck selling the diamond by altering its physical appearance. To note, chemically altered blue diamonds will lose their color over time and will need to be retreated. Mined blue diamonds, however, do not lose their coloring. They really are forever! 


Are Blue Diamonds Rare? 

Naturally mined diamonds can be found in every shade of color of the rainbow. The most common fancy color of diamond found is yellow. Even though natural blue diamonds are extremely rare, they are not the rarest color of diamond in the world. The rarest color of diamond in the world is a red diamond, as less than 30 truly red diamonds are known to exist. Blue diamonds are still exceptionally rare, especially those with grades of Fancy Intense Blue, Fancy Deep Blue and Fancy Vivid Blue. The scarcity of these shades of blue diamonds allows their owners to command extremely high prices. In 2023, Christie’s auction house sold a Fancy Vivid Blue diamond weighing 17.61 carats named the Bleu Royal for $43.8 million dollars


Types of Blue Diamonds 

Like all colored diamonds, their colors are graded on a spectrum of faint to fancy. The intensity of the blue determines the classification of the blue diamond. The color grading for blue diamonds ranges as follows: 

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

Any diamond with a “fancy” grading is going to command a higher premium than a “faint” or “light” colored diamond. However, just because something costs more doesn’t mean it’s better! Should you ever find yourself in the position to select a blue diamond, you should lean toward whatever shade strikes your fancy. 


Where are Blue Diamonds Found?

Most blue diamonds have been mined in India and South Africa, but blue diamonds have also been found in Russia and in Australia at the famed Argyle mine which closed in 2020. 

But the Cullinan mine in South Africa is still operational and yielded one of the most valuable blue diamonds in the world as recently as 2021: the De Beers Cullinan Blue. The diamond was cut into an emerald cut shape and sold at auction in Hong Kong in 2022 for $57.5 million to an anonymous bidder. 


What is the Most Common Shape of Blue Diamond?

Even though round diamonds are the most popular shape of diamond, this isn’t the shape most blue diamonds are cut into. The reason for this is that the cut of a round diamond removes the most raw material when it's made. Diamond cutters are constantly weighing the Four C’s of Diamonds (color, clarity, cut and carat weight) when they decide what shape to cut a raw diamond into. In the case of blue diamonds, it makes sense to retain as much of the carat weight as possible due to their scarcity. This is why you typically see blue diamonds cut into other shapes, such as cushion cuts and radiants. 


Famous Blue Diamonds 

When people think of rare blue diamonds, they almost immediately think of the Hope Diamond, which is perhaps the most famous diamond in the world. The Hope Diamond was discovered in India and the earliest records of the stone’s existence on paper are via French gem trader Jean-Baptiste Tavernier’s purchase of the diamond in 1666. He named the stone the Tavernier Blue and sold it in 1668 to King Louis XIV of France. 

But it wouldn’t be the most well-known diamond in the world if it didn’t have a storied history. In 1792, the diamond was stolen and recut into a smaller shape. The stone has changed hands many times throughout the course of history and many of its owners have met unpleasant or untimely ends, giving the diamond a reputation for being cursed. 

The diamond eventually made its way into the hands of Harry Winston, the legendary American jeweler, and in 1958, Mr. Winston donated the diamond to the Smithsonian Institute in Washington D.C. 


Blue Diamonds in Hollywood 

As blue diamonds are among the rarest and most fabled diamonds in the world, Hollywood films and television shows naturally gravitate toward depicting this color of diamond on the silver screen. Perhaps the most well-known onscreen depiction of a blue diamond in a movie is the fictional Heart of the Ocean worn by actress Kate Winslet in James Cameron’s movie, Titanic. Even though the necklace shown in the movie is supposed to be a blue diamond, it’s actually cubic zirconia, but to their credit, it is a surprisingly good fake. 


A Final Word About Blue Diamonds 

The world has had a long-standing fascination with blue diamonds due to their scarcity, their beauty and their lore. But as you’ve learned, not all blue diamonds are created equal and the ones that have found their ways into the hands of either public or private collections are considered a prized collection amongst owners and admirers alike. 

If you are fortunate enough to have a fancy color diamond in your collection, it’s a good idea to purchase personal jewelry insurance. Jewelers Mutual personal jewelry insurance policies will protect that fancy color gem against loss, theft, and damage! Check your rate online today using the button below.

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