CLARKSBURG, W.Va. (WBOY) — A popular idea, especially in West Virginia, is that diamonds are made from coal. However, is that actually true?
The short answer is no, but the reason why is still quite interesting.
Almost anyone can tell you that both coal and diamonds grow in the ground and are nearly pure carbon. However, that’s generally where the similarities end.
Coal is found much closer to the surface than diamonds, which normally have to be pushed up toward the surface until miners can reach them. Diamonds typically form so deep into the earth that they reach the mantel, around 200 kilometers, only ever leaving that depth thanks to the eruptions of special volcanoes called kimberlites. One of the ways that the carbon necessary for diamonds reaches the mantel is by the subduction of a tectonic plate.
Another theorized source of diamonds is meteor strikes, which may be able to reach the appropriate temperature and pressure for diamonds to form.
Although the exact numbers vary, “diamonds require temperatures of about 2200 degrees Fahrenheit, and pressure of about 725,000 pounds per square inch,” according to dmia.net. This is far above what is required for coal.
Diamonds are also much purer. The carbon in coal comes from decomposing plants, which introduces a lot more impurities and contributes to its darker color.
Another difference is atomic structure. “The bonds in diamonds are held in such a tight structure that all light passes around them, which is why diamonds look transparent,” according to askanearthspacescientist.asu.edu.
So how do we grow our own diamonds?
According to gia.edu, two major methods for creating lab-grown diamonds are “high-pressure, high-temperature” (HPHT) and “chemical vapor deposition” (CVD).
HPHT is exactly what it sounds like, recreating the conditions that form a diamond. A specialized growth chamber adds the necessary heat and pressure to a source of carbon and some metal, which melts together and crystallizes on a diamond seed or waiver, growing it.
CVD also involves using a growth chamber but requires much less heat and pressure. The chamber is filled with a carbon-rich gas and shot with a microwave beam that “causes carbon to precipitate out of a plasma cloud and deposit onto a seed crystal.” This is typically done in cycles of growth and polish over a period of weeks.
These lab-grown diamonds differ from natural ones in microscopic ways but tend to be just as brilliant and functional.
Additional information can be found at he links below:
https://www.gia.edu/gems-gemology/winter-2018-how-do-diamonds-form-in-the-deep-earth
