One of the interesting terms which collectors hear and use is tête-bêche. When a pair of stamps has one stamp printed upside down in relation to the other, stamp collectors use this term.
Most frequently these tête-bêche pairs occur because printers have found it more efficient to produce booklets of stamps by printing sheets of stamps with booklet panes tête-bêche in relation to each other. If these full sheets come onto the market or if there is a miscut of the booklet panes, then the variety pairs become available to collectors.
In the early days of printing postage stamps another way of creating this error happened when the die of a stamp was accidentally transferred onto the printeg plate upside down. The early classics of France produced several tête-bêche pairs which are well beyond the financial reach of most collectors.
Our special features shows what can happen with a square stamp. The first general issue of French Colonies in 1859 has a ten cent value in which one stamp is printed sideways in relation to the rest. I don’t know of an English term, but the French catalogues call it a timbre couché.
We offer a Very Fine used pair from the bottom margin with a neat Martinique postmark (Scott #3a $525; Yvert 3a €600).
[Update January 26th — This item has been sold.]