How is cheating possible?

[Sindai]

I find it ... implausible that you can come up to this conclusion ("He gave himself 200 gems every turn") when you have _ONE_ turn file to examine.

That wasn't what he said. He was saying that Norfleet seems to have been resetting the value of his gem stockpiles to 200 whenever he needed to, since most of the gem types he didn't have much use for were sitting at about 200 in the turn file. This seems pretty reasonable, since it sounds like about the simplest kind of edit possible.