Here is a used 2-cent Andrew Jackson stamp. The auction through which I purchased this stamp included two of these stamps, and said that one was grilled and the other wasn't. If you look very closely at the image of the back of the stamp, you may be able to make out a fine grid. Or maybe it's just wishful thinking on my part. If it has a grill, it would probably be a Scott 87, with a catalog value of about $175 in 2005. If it doesn't, it would probably be a Scott 73, CV $50.

Update: I showed this stamp to my dealer. He looked closely at it and said that he thinks it is grilled. However, it appears that somehow the grill got flattened, and it would be very hard to measure it for a definite identification. Please keep in mind that I do not guarantee the identification of this stamp.

Another update: The little white spot on the center of the right edge was dust or something. I just brushed it off.