Sunita, "The Formation and Color of Diamonds"

Diamonds, formed by the element, carbon, are the most valuable gemstone that has been created naturally due to its beauty, rarity, and great resistance to destruction or corrosion. Diamond is the hardest natural material, being able to cut glass, and therefore is very useful for jewelry. Roughly 49% of diamonds originate from central and southern Africa, although some have been discovered in Canada, India, Russia, Brazil, and Australia. They are insoluble in water, oil and other solvents and are unreactive. However, under certain conditions they can be ignited and then burn to form carbon dioxide. The diamonds are found deep under the earth’s mantle due to their stability of high temperatures and in high pressures in a molten metal such as iron or nickel. Diamonds are bonded carbon atoms which have been crystallized, inside the molten metal, into the face centered cubic diamond lattice structure. Even though graphite is also made out of carbon, it is not hard because it is not stable enough under high temperatures and high pressures, allowing it to become a very soft material. Therefore, both the diamonds and graphite do not easily interconvert because they both contain strong bonds that must first be broken in order for the transition to occur.

Diamonds are purely colorless. If there are any colors in the diamonds, it is due to the impurities that were trapped inside the crystal when it was forming. 1 For Example, a diamond may have a yellowish tinge if it contains some iron oxide as an impurity which can be seen when light strikes certain angles of the diamond. A fact is that a diamond surface reflects about one sixth of the light that hits it whereas glass reflects 4% of the light that hits it. To test the reality of a diamond, an expert can conclude which diamond is real and which is fake by placing their tongue on the diamond. A real diamond would feel cool, like a metal, because diamonds are very good heat conductors as they conduct heat away from your fingers as you touch them. However, diamonds do not conduct electricity well.

I think that this article was very interesting because you would not expect jewelry to be produced from elements that have been formed under the ground. The hardness of the diamond is extraordinary as they can cut through glass whereas the same element, carbon, is used to produce graphite which is very soft and dominantly used in pencils.

Braid. Chemistry in Your Life. 2nd ed. New York, USA: W.H.Freeman and Company; 2006. pp 195-196.