In an intersting bit of surprise, I've done some lapping to the rough surface of the stone. Here's what it looks like now after lapping on DMT XXC….
http://i1152.photobucket.com/albums/...psy1x4syij.jpg
http://i1152.photobucket.com/albums/...psotipcg0i.jpg
The darker spots are just where the DMT plate was contacting the stone during lapping.
http://i1152.photobucket.com/albums/...ps7an3gxxv.jpg
http://i1152.photobucket.com/albums/...psosxyhpc3.jpg