I am not familiar with that particular stone, but all stone reacts differently. It's not just whether it is granite or not. I know that some of the Chinese marble has to be installed with epoxy thinset and not regular as the water content messes it up. Marble is not granite, but my point is the same. Ask the supplier.
The darkening from the moisture is to be expected in any stone and most obvious in the lighter colored ones.
R