Natural diamonds form using carbon, heat (1,100 degrees celsius), and pressure (725,000 psi), but did you know that these gems are also billions of years old? Once you add together the special circumstances of the formation, migration, and true age of the natural diamond, it’s easy to understand why they are so sought after and why the most beautiful ones are so rare.
Even though diamonds can be created in several ways, only a few meet the high standards of qualification to sparkle on a finger or dazzle from an earlobe. Here are three ways that these mesmerizing gems are formed using the necessary, and extraordinary, ingredients.
1. Dig Deep… Really, Really Deep
At about 150 km below stable continental plates, in the upper mantle of our planet, lies the Diamond Stability Zone. Most gemstone-quality diamonds are thought to come from this area and are thought to be anywhere from 1 to 3.5 billion years old. By comparison, the deepest humans have ever drilled was about 122 km, and the goal of that was more about ‘seeing if we could’ rather than digging up diamonds.
Humans don’t have the technology to drill to diamond-harvesting depth, so we depend on another type of delivery system – deep source eruptions that allow the flow of magma (and diamonds) up to the earth’s surface, or at least close enough that we can access our coveted shiny rocks. Most diamond delivery has happened through kimberlite eruptions, which is believed to be a fairly violent affair that can produce so much vapour and gas that a depression is formed in the ground. These eruptions may pass through a diamond stability field and pick up some shiny friends along the way.
2. Where Oceans Meet the Land
Subduction zones, where one plate is pushed deeper into the Earth by another, can create enough heat and pressure for diamonds. The diamonds found in these very rare rocks that have made their way back to the surface do not have commercial use and are small in size – nanometers wide. Not nearly as exciting as a volcano spitting diamonds right out of the earth, these extremely small microdiamonds have more value to geologists than to jewellers.
3. Diamonds in Space
The solar system and beyond is rife with diamonds; it’s even speculated that there could be entire planets composed of diamond material. Now there’s some bling!
Extraterrestrial diamonds come in all sizes, from a few molecules to, well, potentially planet-sized and larger. Diamonds are found in many interstellar vessels from meteorites to stars–including at least one star believed to have a diamond core.
There’s also a possibility that planets within our own neighbourhood experience diamond rain. Uranus and Neptune are suspects, along with Saturn, to have the phenomenon. We love diamonds, but would perhaps skip being caught in a diamond downpour. It would take a special umbrella to endure that storm.
Small, usually valueless diamonds can be found on the Earth’s surface around asteroid impact sites. These diamonds can be formed in space via various ways, and there is potential for diamonds to be created using the energy and materials supplied by the impact. Some may be useful for industry, but, generally, diamonds at impact sites only have scientific value.
What Are the Chances?
Let’s put all of this together. Out of the vastly countless diamonds within our universe, one or a few have made their way to you. The chances of a specific diamond being on earth, caught in a volcano, brought close enough to the surface, and then being mined, inspected, cut, polished, and placed into a beautiful setting just for you is astronomically small. No wonder that gem is so special!
For the record, no, you cannot place a lump of coal in peanut butter and expect to get a clear gem. Coal is not believed to be a factor in diamond creation at all since many of Earth’s diamonds were formed before plants appeared on the planet.