[VLM]

Another argument is on a total mass of carbon basis, diamond and graphite don't exist in nature in large quantities. Most of it is in the form of various boring minerals, coal, CO2, and living material. Refined pyrolytic graphite doesn't exactly wash up on shore and diamonds are very unusual on a tonnage basis.

I'm too lazy to run the exact numbers but its going to work out to something like a trainload of coal per diamond on a total mass of the earth basis.