>>501761I understand your perspective of complete geological and chemical ignorance, but they are still diamonds. Take it from someone who actually has made a fortune with mineral and ore deposits. Like all this crystalized gold I bought off of hippy gem traders for pennies to the dollar, pic related. They didn't have a clue what they had!
>>501937In all seriousness, I'd guess it is a mix of iron oxides and other impurities.