I'm confused by this card and the rules aren't clear. Does the stone reserve count as 1 stone resource, or does it mean I can buy the stone resource at a cost of 1 coin per resource needed or is it both?
The rulebook description seems pretty clear to me:
This card changes the trading rules for the indicated resource. Start
ing on the following turn, you will purchase the indicated resource
from the bank at the cost of 1 coin per unit.
as opposed to the resource card description:
This card produces the raw goods represented.
So, no - it doesn't count as a resource.