How can a diamond and graphite be so different if they are both pure carbon?
Graphite and diamonds go through different processes in their formation. Carbon-bearing materials are subjected to intense pressure deep down in the lithosphere (there are other ways for diamonds to form, but mainly they’re formed in the lithosphere). This eventually produces a diamond. Graphite, if it were exposed to these conditions, could become a diamond. But it is not a diamond yet. You could make a simple comparison to clay. A clay bowl and clay from a river have the same chemical properties, but they are clearly different. River clay could be formed into a bowl and fired, thus producing another clay bowl. But until someone does that, it’s not a bowl; it’s just clay.
