Black Diamond- Composition, Properties and Utility

We all love to wear diamond jewellery. It becomes more fascinating when the diamond appears to be black. Today the black diamond is a very common form of coloured diamond and we have seen its use in various designs of jewellery. Let us have a look at the composition, properties, and use of this kind of diamond. The natural substance which is popularly known as black diamond is actually Carbonado. This impure and poly crystallized form of diamond is the hardest natural diamond.  Generally, we find it in nature as isometric cubic Crystals. 

Where do We Find Black Diamonds?

Black diamond was first discovered in Brazil in the year 1841. Later it was found in the Central African Republic. Alluvial deposits of younger sedimentary rocks are the places where we can find Carbonado. Brazil and the Central African Republic were previously not separated by the Atlantic ocean. These two localities primarily had a common geological setting. Even today these are the places where we find black diamonds


Carbonado contains Diamond, Graphite, and amorphous Carbon too. Generally, mantle minerals like pyrope and forsterite are absent in Carbonado, unlike other diamonds. Physical. 


Black diamonds are superiorly strong and hard. Its clarity is low. This kind of diamond is opaque or turbid. This type of diamond is composed of randomly oriented Diamond Crystals. Carbonado has more porosity than any other form of a diamond. Its surface appears to be irregularly torn. Black diamond contains thousands of microscopic fractures inside it. These fractures increase their vulnerability for breakage. In simple words, we can say that the black diamond is composed of many tiny black Crystals. This kind of crystallization hampers light refraction.


We find Carbonado in five major sizes. One of these is more than 200 ct and the others within 75-95 ct, 25-35 ct, 8-15 ct, and 0.25-1.25 ct. Among them some are elongated and some are rounded.


Carbonado can be of various colours. These are black, putty grey, different brown shades, deep purple, rusty red, and even olive green. Commonly the colour of the black diamond appears to be black and dark grey.  In recent years there have been numbers of research on the reason for its colourization. The study reveals the hat the concentration of graphite, pyrite, and hematite gives Carbonado the unique black look and metallic appearance. The graphitization process induced by High temperature and low pressure can change its colour. This artificial process can darken the colour of green or purple or brown Carbonado and give that a proper black look.


Porosity indicates the amount of void space in a substance. When porosity increases the density of the substance decreases. Black diamond has more porosity than any other form of a diamond. 


Lead isotope analysis shows the history of the crystallization of black diamonds about 3 billion years ago. There is a huge controversy among specialists about the origins of this kind of diamond. So there are different theories of its birth. We still find no unanimity of opinion regarding it. The theories are as follows. 

  1. Some believe that in the earth’s interior, with high pressure, organic carbon underwent a conversion. Thus organic carbon was converted into Carbonado.
  2. Some of the scientists believe that shock metamorphism is the reason for the birth of black diamonds.
  3. Some others say that radiation is the reason for the creation of this kind of diamond. They opine that spontaneous fission of Thorium and Uranium is responsible for the origin of Carbonado.
  4. Extraterrestrial origin theory is the most popular theory on the origin of Carbonado. This theory says that a long-ago supernova explosion itself was responsible for the birth of a black diamond.

How many types of black diamond are available? 

There are three types of black diamonds that are available in the market. Now let’s discuss briefly these three types.

  • Natural Black Diamond: We also know this type of black diamond by the name of Fancy Black Diamond. This is an absolutely real and natural black diamond. As it is rarely found, it is very expensive. The price differs depending on the density of its colour. Though precious, it appears to be more affordable than other diamonds.
  • Treated Black Diamonds: Carbonado can be of various shades like black, olive green, grey, and brown. The black Carbonado is most attractive and most demanded. So specialists use an official graphitization process to darken the shade of a lighter black diamond. With high temperature and low pressure, the colour of lighter Carbonado cover converts into proper black or green so deep that appears black.
  • Man-Made Black Diamond: As original black diamond is scarcely found, specialists have invented a process to grow it in a lab. Now a laboratory can produce synthetic black diamonds. Useless white diamonds are used here. These colourless diamonds are converted into black diamonds with the help of artificial treatment and scientific machinery. These are more affordable than the original ones. But it does not really mean that synthetic diamonds are very cheap. They also value a good sum, due to the lab expense and use of high-tech machinery.

Use of Black Diamond

Primarily Carbonado was used as polishing material. People used Carbonado for drilling when the Panama Canal was being constructed. In recent years, the use of black diamonds is continuously increasing. Nowadays we often use this kind of diamond in making or designing jewellery. We find a black diamond as the centre stone of an ornament. Designers use them with small colourless diamonds to bring a contrast in the design. The use of black diamond in an engagement ring, earrings, necklaces, and pendants are now very common. Due to its unique look, it gives the jewellery a gorgeous finish. Until the late 20th century, people were not interested in using black diamonds in jewellery. Recently it gained popularity when we saw it in the jewellery of famous celebrities. Jennifer Lawrence, Brad Pitt, and even Angelina Jolie have worn beautiful ornaments designed with black diamonds. 

Way to Identify a Real and Genuine Black Diamond

Unfortunately, there are fake diamonds in the market, which are not actually diamonds. These are merely glass cuttings. So if somebody wants to buy a black diamond he must be very careful. A certified gemologist or a certified Lab can easily identify a real black diamond. We also can take a try with a magnifying glass and a strong source of light. Natural black diamonds will have a salt and pepper effect inside it. That will be clearly visible in the light. Hints of green or blue colour in the diamond are a caution to the buyer. If one sees such a hint while seeing the diamond in strong light he must think twice before buying it.


Diamond is the most attractive stone in the world. Due to its unique colour and gorgeous lustre, black diamonds are becoming more and more popular. Many of us today have a fascination with black diamonds. Jewellery with such a black shining stone has a distinct look. But we must be very cautious while buying such stones as there are many fake traders in the market today.

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