The rarer the plate, the more likely it is someone will make fakes of them to part collectors from their money. Much research has been done by an Italian collector on the history of Vatican plates and a book will be published about the history in 2011.
These are all fake Vatican plates and none of them are close to the real thing. Most have been sold on Ebay and they have obviously been made by many different people. 1, 7 and 9 are all ismaa3 fakes but I do not know who made the others. There are probably more than these few we have photos of and ismaa3 has several other single digit numbers also.
If you have a Vatican plate and you are unsure if it is real or fake, send me a photo and I will pass it on to the Italian experts for comment.