Sam Hardy has an update to his earlier text analysing what Interpol did and did not say about ISIL making '$100 million yearly from heritage booty [conflict antiquities]’ (see: 'Interpol did not claim that Islamic State made $100m-a-year from conflict antiquities'). It turns out the whole claim was false from start to finish:
"Since the claim did not even come through Interpol, it must have been falsely attributed to them in order to lend it legitimacy. I don’t want to attribute it to anyone, yet, because it may have been introduced by an as-yet-unidentified link in the chain. But it came out via Iraq".