It is of­ten thought that di­a­monds form from the com­pres­sion of coal, but these beau­ti­ful gems orig­i­nate from a deeper ge­ol­ogy. The con­fu­sion comes from their sim­i­larly high con­tent of car­bon. Both di­a­monds and coal are made of car­bon, but they form in dif­fer­ent lay­ers within the Earth.

Di­a­monds form in the Earth’s man­tle, around 145 kilo­me­tres be­low the sur­face. At tem­per­a­tures of around 1,050 de­grees Cel­sius, di­a­monds form from car­bon un­der the im­mense pres­sure of the

Earth’s man­tle. Ejected via vol­canic erup­tions, di­a­monds are pushed to the sur­face, hitch­ing a ride on a magma chan­nel ris­ing from the man­tle. Di­a­monds have also been known to come from the sub­duc­tion zone, where an oceanic plate col­lides with a con­ti­nen­tal plate, forc­ing the oceanic plate un­derneath its con­ti­nen­tal coun­ter­part. This process oc­curs at a lower tem­per­a­ture and pres­sure, so smaller di­a­monds are formed.

On the other hand, as a sed­i­men­tary rock, coal is the prod­uct of the de­com­po­si­tion of nat­u­ral ma­te­ri­als such as sea life and plant ma­te­rial. Coal is formed much higher up in the man­tle, and is rarely buried to depths greater than 3.2 kilo­me­tres. Though it would make a great rags to riches story, in the case of di­a­monds, it’s riches all the way. Once cut and pol­ished, di­a­monds present their unique sparkle

The word ‘di­a­mond’ is de­rived from the Greek word ‘adamas’, mean­ing in­vin­ci­ble or in­de­struc­tible Strong bonds Each car­bon atom in­side a di­a­mond is co­va­lently bonded to four other car­bon atoms. Un­der pres­sure Cre­ated un­der in­tense pres­sure and heat, di­a­monds are the hard­est nat­u­ral min­eral.

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