Today, you will find black diamonds everywhere. Because the name black diamond, unfortunately, is used to brand a product, service or market segment, such as tractors, computer software, brake pads, heavy metal music from Stratovarious, even our own black yuppies are called “Black Diamonds”.

So, what happened to the original black diamond – the blackest, most illusive gem legends and folklore raved about, and which often was the crown in a pirate’s loot? In the past, natural black diamonds have been available to those fascinated by the unusual. Today, polished black diamonds are more ubiquitous and are set in yellow or white, even rose gold jewellery.

You may well ask: “What is a black diamond?”

There are three kinds of diamond often referred to as “black diamonds.”

  1. The most accessible type is a dark yellow or brown diamond that had been turned into a dark greenish diamond that looks black, by irradiation and heat. Such black diamonds are difficult to polish and may show polishing drag lines and cracks across facets may be visible to the naked eye. Their girdles are often chipped. They do not sparkle but are extremely hard and combine beautifully with brown, yellow or white diamonds. Some modern couples prefer to buy a large black diamond, instead of a small white one. Their “wow” factor comes from the mystery and lore which black diamonds possess.
  2. The only true black diamond is one which does not transmit any light. Even the thinnest sliver (when held up to a very brightest source of light) will not transmit any light. Such diamonds, if untreated, are extremely rare.
  3. Another type of black diamond is called carbonado which is only found in the Central African Republic (Congo) and in Brazil. Carbonados are made up of numerous tiny black diamond crystals “welded” into a porous aggregate normally the size of a pea.

Their origin is problematic as they do not occur in Kimberlitic volcanoes which are the primary source of diamonds. Some scientists believe carbonados formed in space when two asteroids collided. Others say it formed as a result of shock metamorphism during a meteoritic impact. Geoscientist Dr Stephen Haggerty, proposed carbonados formed during the explosion of a supernova. After drifting through space, a large lump fell to earth approximately 2.3 billion years ago. Upon entry, it broke into millions of pieces which fell in an area in Gondwana, that, much later, would split into the Congo and Brazil – the only two known locations for this type of black diamond.

The origin of black carbonados thus remains enigmatic. When modern scientist cannot agree on its origin it is no wonder the alchemists of old and the scribes of fantasy tales attach such significance to a small black lump of very hard rock.