This chapter made no sense.
She says "The magic stone is created by thousands of magicians pouring their magic into it", which clearly marks it as artificial/man-made as well as a singular object (e.g. There's only one). However they then immediately say it's rare, implying that there is more than one, however since they already established that it was man-made, then why the heck do they show it being found buried in a mountain like a chunk of raw ore?
Further, how the heck is that information worth anything in the first place if the "location" is that it's "somewhere in a giant mountain"?! That's like calling a taxi to pick you up somewhere in New York city. That's near useless. Then you add on top the fact the she says they she found it by "stumbling upon it" when it's clear to anyone that looks at her that she's a city girl... How the heck does a city girl accidentally encounter and identify a rare magic gem buried in a mountain but have absolutely nothing to show for it? (No location details, no sign of ever physically exerting themselves, etc).
Finally, there's no way information sales with such a shady and absurd source would get an upfront down payment for their wild tale. This is either the merchant playing along since he knows who she is, or this is complete absurdity.