I keep running into that word in various marketingspeak I've seen. It feels like one of those words that is sort of airily used without really saying much: "Our positioning will be the touchstone of our strategy and messaging."
I admit I didn't exactly know what a touchstone actually is. If you want to know, according to the actual definition, in the root, literal sense:
a black siliceous stone formerly used to test the puruity of gold and silver by the color of the streak produced on it by rubbing it with either metal.
In the modern, the correct usage would be with this concept at the fore:
a test or criterion for the qualities of a thing
As an example, Henry Kissinger said once that "the qualities of courage and vision that are the touchstones of leadership."
He means if you don't have courage and vision, you're not a leader. To meld the figurative and the literal, you test for leadership by rubbing someone on a touchstone -- if courage and vision don't show up on the streak you leave on the rock, you don't have a leader. According to Henry, that is.
So, I'm pretty sure this is used incorrectly more often than not. I think people who use it are trying to allude to something that is a foundation element, or the nucleus, or some kind of non-negotiable standard-bearer.
Am I right?