How rare are blue diamonds? To find that glittering needle in the haystack, tons of ore have to be unearthed. And when a blue diamond is found, you can imagine the excitement it causes.
The answer is a diamonds exposure to either Boron, Radiation or Hydrogen.
The presence of boron impurities is most often responsible for the colour of natural blue diamonds. The centre photo below shows a natural blue diamond with boron impurities.
Some blue diamonds are naturally coloured by exposure to radiation. These diamonds usually appear with a more vivid green-blue colour.
Diamonds coloured by their association with hydrogen are described as gray-violet to gray-blue (pictured below on the right).
The diamond was stolen in 1792 and re-cut to avoid detection and was then eventually purcahsed by Henry Philip Hope in 1830. Since being purchased the diamond gained the reputation of being cursed and has often been thought to be associated with the deaths of very difficult lives of some of its owners.
This diamond is now known as the very famous Hope diamond and is now housed in the Smithsonian Natural History Museum in Washington, D.C.
India was historically the source for blue diamonds but within the last several years, notable blue diamonds have been found at the Cullinan Mine in South Africa. A few other South African mines have produced blue diamonds and some are occasionally found in Sierra Leone, Borneo - which is off the coast of Indonesia, and Brazil.
GIA’s online Gem Encyclopedia has an entire entry devoted to coloured diamonds.
Thanks to GIA Blog for this fabulous article and photos!
http://4csblog.gia.edu/