I have two pieces of persimmon from different sources, that both a gray color to the in the center.  The larger is a 2 1/2 x 6 billet about 40″ long.  The exterior is creamy white with very little grain except for one thin black heartwood streak.  When I trimmed the end I found that the wood is white for about 1/2″ to 3/4″ in from all faces and the wood in the center has a gray tinge.  No  hardness or other differences except color.  My other piece is 2×2 turning billet about 24″ long.  Same thing, cream colored wood, with a gray cast about 1/2″ in from exterior faces.  Is this common to all persimmon?  Only a problem with air dried lumber?  Does kiln drying prevent it?  
I like the look of the grain, color and hardness of persimmon for the tool handles and rolling pins etc. I have been making. but the gray turns me off.