Now that I think about it, I did turn the area around him to glass, but only to prove to myself that he'd gotten all the valuable ores nearby. This was well after I'd been convinced of xray.
I've reviewed the evidence again and gotten a third opinion.
There are four diamond ore deposits, with direct line paths between them, in non-linear paths. You got EVERY diamond ore deposit within 20 blocks, and were headed toward a fifth. The diamond deposits are on "corners", which means you went to an ore, mined it, then changed direction and went to another ore. Three times.
Mods, see ticket 2474 if you want to examine the evidence.