A Very Common Element and Very Uncommon Conditions
Diamond, the mineral, is fascinating to begin with. The very hardest of substances, and the best known conductor of heat, it is formed of nothing more than elemental carbon, the same substance that provides the basic chemistry of every living thing. The material from which pencil lead is made. We exhale its oxide with every breath. 87 -100 miles deep underground, the earth's crucible applies fantastic heat, stupendous pressure and time — more than a billion years. In just the right combination, with the presence of sufficient carbon, these forces can create a small deposit of eight-sided crystals, called diamonds.
Special Delivery By Volcano
Only where volcanic action has propelled them towards the earth's surface are diamonds recoverable. Although extremely rare and very difficult to find, the vast majority end up in industrial applications, cutting and polishing — the most effective of all abrasives. The purest and most flawless examples, of adequate size, can be cleaved, cut and polished to unparalleled brilliance — to become diamond, the jewel. The ultimate jewel. Or are they?
Something 10,000 Times Rarer
Now, imagine another jewel typically 10,000 times more scarce, and arguably even more beautiful. A gem-quality colored diamond. It is the product of all those same geophysical forces and fortunes — plus an added influence. Each color occurs for a different reason. Its extremely rigid lattice permits only a rare few additions to the formula, and then in such miniscule amounts (one atom in a million) as to be ignorable — except for the color. The delivery volcano also plays a role in the final color. A difference of as few as 100 degrees Celsius can take diamond from one distinct color range to another.
A Reason For Every Color
Yellow or orange diamonds are caused by nitrogen. Boron yields a range of blues. Brown results from lattice defects. The presence of hydrogen produces unique violet hues. Unusually high pressure can abnormally compress a diamond's structure, to create red, pink, purple or brown coloration. Some stones are dubbed "cognac" for their color similarity to fine, aged brandy. Natural radiation passing through already formed diamonds for millions of years can impart a green hue.