This word “transparent”. I do not think it means what you think it means.
Edit:
Perhaps I should explain my comment. The two 4 cent Lincolns shown look remarkably like some fakes I ran across at a coin shop near Copenhagen several years ago. Looking closer at the images, I think that both the adhesive has completely worn off, and the stamps were submerged in water for some time, giving a “see through” quality to them.
My experiences with stamps is limited, however. I could be wrong on all counts.