A specimen stamp is a postage stamp or postal stationery indicium sent to postmasters and postal administrations so that they are able to identify valid stamps and to avoid forgeries.
The usual method of invalidating the stamps is either overprinting in ink or perforating the word Specimen across the stamp. (From Wikipedia).
Also specimen stamps are made in very very limited quantity, but looks like following SPECIMEN stamp was made in large quantity as I have seen multipe stamp full stamp sheet as well as single stamp or incomplete stamp sheet.
Not sure how postmaster or postal administrators will validate stamp or identify forgery using following Specimen stamp with all kind of missing information such as issuing country, value of stamp etc....!!!
Not sure from which country this Specimen stamp is from!! But to me it looks like selling by eBay seller from Germany and Australia.!!
In past I wrote following blog posts about this Specimen stamp and to me it looks BOGUS Briefmarken (stamp). (Bogus stamps are pretended, fictitious stamps which purport to be produced by an entity that exists and could have produced them, but didn't. A bogus stamp is not a forgery because it never really existed. Here ENTITY also does not also exist.!! so it's Extra Bogus.!!)
In past I have seen complete stamp sheet of 100 Gandhi Specimen stamp was not even sold for 2000 Euros.!! (20 Euros per stamp). Also similar sheet was for sale for $15000 - $45000.!!
So how stamps are sold and how we know what is the real value?
Also in past this kind of single stamp was sold from 30-50 Euros from seller Germany eBay seller and bought by some famous Gandhi Briefmarkensammler (stamp collectors).!!!
Following screenshot will show you that eBay seller "edva52" sold single stamp for 49 Euros.!!! to "suratphilatelist", "coolblue1955" and "akhilesh_1983"
Update :- In Feb 2014, there were 400 stamps were for sale.!!