My 5 yr old son did this with a black sharpie on 3 types of stone at his grand parent's house (YIKES!): grey polished slate, varnished marble bowl, white granite with no finish. It came off of the slate the easiest and the varnished granite using 409, dish soap, and one of those "Magic Sponges". The white marble was porous and soaked in the sharpie dye/ink.