According to this article of the Philatelic Webmaster Organization, some printing companies have made deals with poor countries (mostly in Africa) to print stamps that are mostly targeted to the stamp collecting market. The stamps are apparently endorsed by the local postal administrations, but are printed in huge quantities (compared to the local needs of the country), and sold mostly to collectors. The article in particular cites the Swiss printing company "Impressor SA". I indeed have seen their label on many topical stamps and souvenir sheets related to minerals, from countries like Chad, Comorros, Mali, Niger, Congo... The design of those stamps and souvenir sheets are strikingly similar, and one could wonder if they were not only printed by the same company, but designed by the same company as well. If all this is correct, then one could also wonder how much philatelic value those stamps really have. :-(
Some examples of questionable topical stamps with minerals printed by Impressor SA:
"République Fédérale Islamique des Comores"
"République du Congo"
"Repoblikan'i Madagakasikara"
"République Centrafricaine"
Some examples of questionable topical stamps with minerals printed by Impressor SA:
"République Fédérale Islamique des Comores"
"République du Congo"
"Repoblikan'i Madagakasikara"
"République Centrafricaine"
