“Glorious Mother Country,” 4th series: Major inventions by ancient and medieval Chinese scientists: Seismoscope, later Han Dynasty - 伟大的祖国, 第四组：中国古代和中世纪科学家的主要发明：地震仪，后汉 $800 Dark green
- Country People`s Republic of China
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Denomination
?$800Face value of a stamp, usually printed on the stamps.— Glossary
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Color
?Dark greenOriginal catalog color of the stamp.
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Print method
?EngravedMethod of process of imprinting designs on paper.
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Perforation
?14Holes punched between stamps to make separating easier.
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Watermark
?UnwatermarkedA pattern embedded in a paper during stamp producing process.
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Issue Date
?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.
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“Glorious Mother Country,” 4th series: Major inventions by ancient and medieval Chinese scientists: Compass, 3rd Century, B.C. - 伟大的祖国, 第四组：中国古代和中世纪科学家的主要发明：司南，战国时代 (公元前 300年)
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