I understand the Blue Agate scarcity due to blue not being readily found in nature.
Yes, in the scientific sense, there are differences between lets say, Diamond and Granite. But the stones being used by Koetsu are not 'that' dissimilar . They are and must be for machining purposes, the same! We are not listening at this 'Atomic' level. There are more vibrations in the air from just the movement of the 'air' itself than what will be heard by humans at this 'atomic' level of stone.