We are trying to decide on a black granite for our kitchen countertops. Aside from the appearance, I am concerned with durability of the granite. I tested samples of Marron Cohiba and Volga Blue with red wine vinegar and red wine. After cleaning off the test substances, Marron Cohiba showed a shadow of the complete test areas. There was no evidence of test substances on the Volga Blue. My husband wonders if the Marron Cohiba wasn't sealed well? Both granite samples have high shine, are completely smooth to the touch, and passed the hit-it-with-a-sharp-metal-object test. Does anyone have info on the durability of these two granites, and what it means that the wine and vinegar left spots on Marron Cohiba?