Hard disagree: they exhibit 4 perfect octahedral cleavage planes in addition to their adamantine lustre, diamond is one of the most useful materials in existence, and their petrological origins speak to incredibly interesting conditions of formation! In fact, a mineral inclusion within a diamond gave us our first solid evidence of the existence of water at equilibrium with mantle rock at depth on Earth, which was previously largely discounted.

But yeah, fuck De Beers.