Chemistry sometimes takes some strange twists and turns. Recently I learned of a rather bizarre connection between the part of sub-topic 4.3 that includes the allotropes of carbon and Option B: Human Biochemistry. Perhaps the one thing that is certain in life is that no one is immortal. Eventually the second law of thermodynamics kicks in – or does it? Now, if you wish, your cremated remains can be turned into a  diamond – and, according to Ian Fleming and James Bond, “Diamonds Are Forever”.

A rough, uncut diamond synthesised from human remains - image from Algordanza

99% by mass of the the human body is made up from just six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. The most abundant of these is oxygen but carbon makes up about 18.5% by mass. When a body is cremated the 5 kg or so of ashes (known as “cremains”) still contain a considerable amount of carbon, although the exact amount does depend upon the precise method and temperature of cremation. To make a diamond about 0.5 kg of the ashes are required and if there is insufficient carbon it can be added to by using a lock of hair. After extracting the carbon it is purified to 99.9% purity. Then, using a tiny existing diamond as a ‘seed’, it  is subjected to high temperatures and pressures that are in the region of 1370 ^oC (2500 F) and  6 x 10⁴ atmospheres (6 x 10⁹ Pa) for several weeks to produce a rough, uncut diamond. If the customer so wishes, the diamond can then be cut and polished and placed in a setting. The diamonds that are made this way tend to have a distinctive blue colour due to traces of boron in the purified carbon. The cost of making a diamond from cremated remains depends upon the size but starts from about €4500 ($5300 ). As well as human “cremains’ diamonds can also be made from the cremains of pets.

Cut and polished diamonds synthesised from animal "cremains" - image from Algordanza

One of the companies that performs this service is Algordanza, which is based in Switzerland. A resumé of the whole process can be found in an article by Dave Mosher in Business Insider Today. You might like to ask your students to comment on the explanation given in his article attributed to a spokesperson from Algordanza as to why it is nearly impossible to separate boron from carbon, “This is because the two elements share similar weights and properties.” This is then followed by the following image: