Diamonds – shining and ancient

How the “unbreakable” mineral was created

Di­a­monds as jew­el­ry have been known to hu­man­i­ty for a long time – 5,000 years. This min­er­al stood out from oth­ers for its unique beau­ty, and for cen­turies it was a sign of wealth. Let’s take a clos­er look at them.

What is a di­a­mond?

The word “di­a­mond” comes from the An­cient Greek “adamas”, which means “un­break­able”. In­deed, in or­di­nary con­di­tions, the min­er­al can main­tain a sta­ble state for an un­lim­it­ed amount of time. Di­a­monds are the hard­est but also the most frag­ile min­er­al known to hu­man­i­ty. The min­er­al is used in var­i­ous fields of in­dus­try be­cause of its hard­ness (di­a­mond cir­cles on met­al, use in elec­tron­ics). An in­ter­est­ing fact is that most di­a­mond jew­els have a yel­low or brown tint. Peo­ple have even learned to make ar­ti­fi­cial di­a­monds. They are made and elab­o­rat­ed un­der colos­sal pres­sure.


Di­a­monds are a rare min­er­al, but can be found all over the world. Di­a­mond mines can be found ev­ery­where but Antarc­ti­ca. Sci­en­tists are still puz­zled by the for­ma­tion of the min­er­al – what nat­u­ral phe­nom­e­non caus­es di­a­monds to form?

A sim­ple ques­tion which is dif­fi­cult to grasp: how can a di­a­mond burn?

In­deed, is this ac­tu­al­ly pos­si­ble? You can’t just take the hard­est min­er­al on Earth and burn it. But even if you could, why would you want to? Let’s look at sev­er­al dis­cov­er­ies which were made in the past.

Through the ages

Be­fore the 17th cen­tu­ry, di­a­monds were re­gard­ed as a sub­stance that had noth­ing in com­mon with graphite or coal. The sci­en­tist Axel de Brut, and lat­er Isaac New­ton, be­lieved that the min­er­al could burn. They came to this con­clu­sion from ob­ser­va­tions of the re­frac­tions of rays of tur­pen­tine and cam­phor.

In 1694, Flo­ren­tine sci­en­tists con­duct­ed an ex­per­i­ment to find out what would hap­pen if they put a di­a­mond in the fo­cus of a con­cave mir­ror. They achieved the de­sired re­sult – the di­a­mond be­gan to smol­dered, and af­ter fur­ther heat­ing, the the­o­ry be­came re­al­i­ty – the di­a­mond burnt down com­plete­ly.

Sci­en­tists at the time did not draw the cor­rect con­clu­sions from the ex­per­i­ment, as they be­lieved that di­a­mond and quartz were the same sub­stance, with dif­fer­ent types of in­ter­nal struc­tures.

In 1772, An­toine Lavoisi­er held a sim­i­lar ex­per­i­ment to show the sci­en­tif­ic com­mu­ni­ty that the the­o­ry was cor­rect. Cre­at­ing the con­di­tions for the ex­per­i­ment did not take him much time or ef­fort – he only re­quired a large lens, a sealed boil­er and the help of sev­er­al as­sis­tants. Lavoisi­er’s op­po­nents hoped that he would fail, but the ex­per­i­ment was a suc­cess. The stone dis­ap­peared from the ef­fect of the sun’s rays, which made Lavoisi­er con­clude that it had turned to gas.

Antoine-Laurent de Lavoisier (1743-1794) [Flickr]

In 1797, Smith­son Ten­nat made a sim­i­lar ex­per­i­ment. He took a gold pot with a pipe at­tached to it, and oxy­gen was pumped into the pot. Ac­cord­ing to his cal­cu­la­tion, by grad­u­al­ly adding oxy­gen, the min­er­al would trans­form into a gaseous state, i.e. the di­a­mond would turn to gas, just like when coal was burned. The ex­per­i­ment was a suc­cess, as it had been for Lavoisi­er. The gas in the pot was car­bon diox­ide, which con­firmed his sup­po­si­tions. The the­o­ry worked.

The sci­en­tist De Morveau also con­duct­ed stud­ies in this field. In his ex­per­i­ments, the sci­en­tist also de­cid­ed to burn graphite, which had a car­bon con­tent of over 99.5%. De Morveau found an in­ter­est­ing cor­re­spon­dence – if iden­ti­cal con­di­tions were cre­at­ed for burn­ing graphite, di­a­mond and coal of iden­ti­cal weight, then the same amount of car­bon diox­ide would form. Here you'll find easy and safe ex­per­i­ments on ob­tain­ing beau­ti­ful min­er­als.

Just car­bon

We may of­ten won­der why car­bon diox­ide is formed when di­a­monds are burnt. The ex­pla­na­tion is sim­ple: di­a­monds are an al­lotrop­ic form (“struc­tural mod­i­fi­ca­tion”) of car­bon. Here is di­a­mond’s crys­tal struc­ture:

Diamond animation.gif

In­deed, di­a­monds burn in the open air at a tem­per­a­ture of 850-1000 °С, and in pure oxy­gen at 750 °С.

A fi­nal word about safe­ty

Re­mem­ber that the ex­per­i­ments de­scribed in this ar­ti­cle were con­duct­ed by pro­fes­sion­als in the field of chem­istry, even if this did take place a long time ago. We don’t rec­om­mend re­peat­ing them just to find out what the re­sult will be. We strong­ly rec­om­mend that you re­frain from con­duct­ing ex­per­i­ments of this kind your­self, as there will be un­fore­seen and un­pleas­ant con­se­quences.