Diamond is one of the many allotropic forms in which carbon can appear; in particular, the diamond is constituted by a crystalline lattice of carbon atoms arranged according to a tetrahedral structure.
It is thought that diamonds were initially recognized and extracted in India, where they were found in alluvial deposits along the Krishna and Godavari rivers. Diamonds were used in religious icons and are likely to be known and considered precious as early as 6,000 years ago.  In fact there are references to diamonds in Sanskrit texts: the Arthashastra of Kautilya mentions the trade,  Buddhist works from the 4th century BC. onwards they describe the diamond as a very well-known and precious stone, even if they do not contain indications about cutting techniques. 
Another Indian text written at the beginning of the third century describes strength, regularity, brilliance, the ability to scratch metals and good refractive properties as desirable qualities of a diamond .
The Indian city of Golconda was for centuries and until the mid-nineteenth century the main center of production and sale of diamonds, so that its name was synonymous with wealth.
Diamonds came to ancient Rome from India and there are clear references to their use as engraving tools.  
The Chinese, who did not find diamonds in their country, did not consider them as jewels in the past, while they appreciated jade a lot. A Chinese work of the III century BC he quotes: "Foreigners wear them [diamonds] in the belief that they can remove evil influences from them". 
Until the eighteenth century the diamonds came exclusively from India or Borneo and only in 1725 in Brazil, in the State of Minas Gerais, were found the first diamonds from South America. Later, in 1843, carbonado was found, a diamond-black microcrystalline aggregate, used in industry.
The first discovery in South Africa occurred in 1867, near the sources of the Orange River, and until 1871 only alluvial deposits were exploited. Later it was discovered the existence of the diamond chimneys, of which the best known is the Kimberley mine which gave its name to the mother rock of the diamond, the kimberlite.
In the eighteenth century deposits were discovered in Borneo, which began the diamond trade in Southeast Asia. With the depletion of Indian resources, significant discoveries took place in Brazil (1725) and South Africa (Kimberley, 1867).  South Africa therefore became the main world center for the production of this precious gem. 
The popularity of diamonds has increased since the nineteenth century thanks to the increased supply, the improvement of cutting and polishing techniques, the growth of the world economy and also thanks to innovative successful advertising campaigns.  In 1813 Humphry Davy used a lens to concentrate the sun's rays on a diamond in an oxygen environment and showed that the only product of combustion was carbon dioxide, proving that the diamond is a carbon compound. He later demonstrated that at a temperature of about 1,000 ° C, in an oxygen-free environment, the diamond converts to graphite.