For The League of Nations: Helvetia 50c Deep green & pale green

Regular Issue Overprinted

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

50c
Color
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Original catalog color of the stamp.

Deep green & pale green
Print method
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Method of process of imprinting designs on paper.

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

11 1/2, 12
Watermark
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A pattern embedded in a paper during stamp producing process.
— Basic philately terms for amateurs

Swiss Cross
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.
#
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Catalog number of stamp.
— Basic philately terms for amateurs