What's the Difference Between Diamonds and Coal?

Most diamonds that we have are not the by product of coal getting squeezed, because coal is actually a relatively late addition to the earth's crust. You can assemble these little bits of carbon in lots of different ways that have lots of different properties at the microscopic level. And if you start from carbon and you get them under really intense heat and pressure, they will form this really interesting structure which will then survive when it goes back down to lower temperature. It takes this energy to build it, but once it clicks into place, it's super duper strong.