When purchasing unused 19th century stamps with no gum you must be VERY careful. A friend of mine who certifies stamps for one of the larger companies told me that actually less than 20% of 19th century stamps...
When it comes to early mint stamps re-gumming has proved to be a most persistent problem. Re-gummed stamps are worth far less than their counterparts with original gum. A re-gummed stamp is a stamp with...