Everything You Need to Know About the Mysterious Blue Diamond

3 min

Blue diamonds. Yes, they exist although incredibly rare these high-value gems are as beautiful as they are rare. Despite the unique color, blue diamonds are not man-made and form in nature when boron, as well as nitrogen, come together. Depending on the amount of nitrogen the tone can look richer and deeper. It is interesting to note, that blue diamonds are held in high esteem in the gem community as well as by scientists. These sea-colored gems have been found to be the highest conductors of heat and electricity.


In 1903, blue diamonds were first discovered in the Cullinan mine in South Africa. This is where the famous 12-carat piece. The Cullinan I and II are now a part of the royal family kept in the cache of Britain’s crown jewels.

Just last year, blue diamonds were also found 400 miles beneath the ocean floor where years of heat, pressure, and boron came together to create these mysterious blue gems. Still, they remain quite elusive as less than .02% of diamonds that are mined are blue.

Famous Blue Diamonds

As mentioned Cullinan I and II are part of the royal collection but there are other famous blue diamonds.

  • The Hope Diamond – Harry Winston donated this 45-carat heavyweight to the Smithsonian in 1958. Valued at $250 million
  • The Heart of Eternity – Over 27 carats and cut into a heart, this blue diamond was found in the Premier Diamond Mine in South Africa and cut by De Beers.
  • The Imperial Blue – Flawless and weighing a little over 39 carats, its value is a modest $79 million!
  • Blue Moon – This unique piece was sold by Sotheby’s for $48 million, like other famous diamonds when exposed to UV light it emits a red phosphorescence

How to Choose a Blue Diamond

Unlike traditional colorless diamonds, colored diamonds, require different specifications prior to purchase. These are not only beautiful pieces they are also incredible investment opportunities, so before you leap learn what to look for in a blue diamond. Here is a quick checklist:

According to the industry leader, the Gemological Institute of America, the value of a blue diamond is based on 4 main factors:


When it comes to fancy colored diamonds, the color of the diamond is the most important element. The grading for colored diamonds is as follows:

Fancy Light, Fancy, Fancy Intense, Fancy Vivid

For blue diamonds, the stronger or richer the color the more expensive, but these are exceptionally rare and hard to find.


Right behind color is clarity in terms of importance for fancy colored diamonds. This refers to how many inclusion is found within the diamond. Blue diamonds typically have almost no inclusions. For example, you can purchase a beautiful blue diamond from Astteria that has an IF clarity rating which means it is flawless up until 10x magnification.


The cut and setting of any diamond are important. When it comes to colorless diamonds cuts are critical as a dull or incorrect cut can dull the diamond leaving it without any light performance. For fancy colored diamonds, the light stays inside sore more color shows.

Special machines and experts are brought in to analyze, cut, and polish diamonds to maximize their ultimate color and sparkle. Shape and cut are different. Shape refers to the outline while the cut refers to facets, symmetry, dimensions, and any other reflective attributes.

A Radiant shape is a perfect choice for colored diamonds. While cuts can vary, pear and heart appear to be very popular for blue diamonds.

Carat – refers to the weight of the diamond itself. The current price for a blue diamond is $100,000 a carat.

Since blue diamonds are excellent investment pieces be sure to review all the necessary criteria carefully. 


Always do your research and make sure that the jeweler you are doing business with is accredited and backed by substantial positive reviews. Sadly there are many dishonest dealers who can easily sell blue sapphires or lab-created stones, so do your due diligence.

Always have your jewelry looked at by a certified and trusted gemologist. Here are just a few questions to ask before choosing your jeweler:

  1. Are they knowledgeable? If your jeweler looks confused or mixes up basics like cut vs clarity excuse yourself and run out. A jeweler should be a competent and trained gemologist.
  2. Are they certified? Always ask for a third-party diamond certificate this is usually from the GIA or other industry-standard leaders.
  3. Do they want to educate you or just sell you something? A jeweler who is any good, will want to explain the basics of the 4 c’s and help you understand what to look for.
  4. What metals do they use? The diamond is precious but placed in a poor quality setting could mean bad news. Look for stamps that let you know what quality cold or other metals you are being sold.
  5. Are they trustworthy? Get references, look online, and most of all trust your gut.


The spectacular blue diamond is awe-inspiring and can come with a significant price tag. Be sure prior to purchase whether, for personal enjoyment, an heirloom, investment, or all of the above, you review everything about the stone, Color, Clarity, Cut, and Carat will tell you everything you need to know. Then certify the authenticity with a credentialed and honest jeweler.

About the author

Pearl M. Kasirye is a writer at La Dolce Studio, editor, and researcher who spends most of her time reading. When she isn’t reading or working, she can be found sitting on her balcony writing her own novels or traveling.

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