Varieties in Stamps are many. Some of them become quite valuable. These varieties may range from color differences, shades of colors, perforation differences, to whether the stamp was printed on a flat-bed press or a rotary press. There are also plate differences, those caused by damage or wear on a plate causing a slight change to be made. The change was usually not deliberate, but was the result of two different engravers working on the same plate. If a nick was suffered on a plate, for example, an engraver, other than the one who originally did the plate, might have been assigned to repair it. The slight differences that showed up in the subsequent printing of that stamp made it a collectable variety, sometimes a highly priced rarity.
Some times a printing plate will crack, and several sheets of stamps run off and issued before the crack is noticed. These are immediately in great demand among variety collectors since the supply is limited. As soon as the crack is detected the plate is either with drawn or repaired.
Varieties also exist in the kind of paper used to print the stamps. Sometimes the paper was thick, sometimes thin. Some papers were soft and porous, others hard and non-porous. All these things contribute to the creation of varieties which are the delight of specializing collectors, and sometimes the bane of those general collectors who do not recognize the interest or additional value in the differences.
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