For The International Labor Bureau: Mt. Pilatus 5c Blue green

Overprinted in Black

Country Switzerland
Denomination
?
Face value of a stamp, usually printed on the stamps.
— Glossary

5c
Color
?
Original catalog color of the stamp.

Blue green
Print method
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Method of process of imprinting designs on paper.

Engraved
Perforation
?
Holes punched between stamps to make separating easier.
— Basic philately terms for amateurs

11 1/2
Watermark
?
A pattern embedded in a paper during stamp producing process.
— Basic philately terms for amateurs

Unwatermarked
Issue Date
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Date inscripted on a stamp or cancellation for used stamps not necessary correspond to real date of stamp issue.
#
?
Catalog number of stamp.
— Basic philately terms for amateurs