Top 10 Facts about Black Diamonds | Cape Town Diamond Museum (2024)

Book a tour at the Cape Town Diamond Museum to learn more about the history of diamonds and see replicas of the world’s most famous diamonds.

1. Millions of Crystals

Typically, diamonds are a single solid stone, but black diamonds are actually made up of millions of smaller black crystals, bound together by internal inclusions. This is known as a polycrystalline structure and this is what gives them their colour. Spots can sometimes appear dark grey because of this structure.

2. The Toughest of Them All

While all diamonds are known for their strength and durability, black diamonds are tougher than any other diamond. They measure a 10 on the Mohs Hardness Scale, which means they are very difficult to cut and polish.

3. They Don’t Shine

“Shine bright like a diamond” doesn’t quite apply for these dark beauties. These rare diamonds absorb light instead of reflecting it, meaning their beauty comes from their surface which is polished like marble.

4. Found in Only Two Areas

While other diamonds are found in various locations around the world, black diamonds have only been found in two – Brazil and Central Africa. Keep in mind that these two pieces of land were adjacent in prehistoric time, which tells us they are originally from one area.

5. Some Believe They’re from Outer Space

While it is understood how other diamonds were formed, black diamonds are very mysterious and no one is certain as to how they were formed. Some researchers believe that black diamonds were formed in outer space in stellar ​supernova explosions and came to Earth via an asteroid crash between two and four million years ago. They are thought to have been the size of asteroids, a kilometre or more in diameter. Black diamonds contain trace elements of nitrogen and hydrogen, a possible indicator of an extra-terrestrial origin. Other theories around how they were formed include a meteoric impact and radiation.

6. It Can Take One Year to Cut a Black Diamond

Cutting a black diamond can take up to one year and is a very frustrating and time-consuming process. This is because they have an unusual combination of carbon and graphite atoms. So, if you have a black diamond ring, you can appreciate that a lot of time, effort and patience went into creating your beautiful black masterpiece!

7. Exclusively Found in Alluvial Deposits

While diamonds are typically found in kimberlites, black diamonds are unique in that they are only found in alluvial deposits – younger rock formations and only near natural sources of water.

8. Blessing or a Curse?

Black diamonds were thought to be a blessing or a curse, depending on the culture. Ancient Indian people used to consider it a curse because it resembles the colour of a spider or snake’s eyes. On the other hand, Italian people believed that touching a black diamond would bring good fortune to their marriage, and that it was a sign of reconciliation. Today, black diamonds are rarely thought of as a blessing or curse, but rather mysterious and elegant gems.

9. Carbonados Diamonds

Black diamonds are also called carbonados diamonds. The Portuguese in Brazil coined the term carbonado, which means opaque dark diamond, in the mid-18^th century.

10. Similar in Price to Colourless Diamonds

You might be wondering, “How much black diamonds cost?” They were generally more affordable but are now similar in price to colourless diamonds. However, they are not quite as popular due to their lack of sparkle but are still an elegant and sophisticated choice of gem for a stunningly unique and intriguing jewellery piece.