Whenever you are bidding on a stamp on eBay
, particularly a more expensive one (this is not), it is a good idea to make the seller post both front and back images. That way you can assess the condition of the gum, and see if there are any pencil, pen or owner's stamps on it. All of these things affect the condition, and ultimately the value. It also helps to have a catalog so you can have some idea of the relative value of the item.