Rare Stamps. Please click on an image to see a larger version. 1918 - Inverted Jenny This is the world's most famous and rare example of a stamp printed in error. The stamps were printed in 1918, out of which a few were printed with the image of a Curtiss Jenny plane upside down.One,Mr. W.T. Robey purchased an entire sheet worth 24 $, of these 24 cent airmail stamps. He was an experienced collector and he knew instantly that he was sitting on a goldmine when he discovered that the airplane printed was shown flying upside down. Mr. Robey sold his sheet, to one Mr. Klein for $15,000 who, sometime later, sold it to Edward Green for $20,000. Green ultimately retained a block of eight stamps for his own collection and sold the rest of the inverted Jenny's to other collectors. Today, these stamps, has a catalog value of $300,000 each and has privately been sold for as high as $2,970,000 to Bill Gross.He traded it with Donald Sundman for one of only two known examples of the USA 1c Z Grill. 1885 - Tre Banco Skilling A 14 year old Swedish boy named Georg Backman first discovered the Skilling Banco - Sweden's first stamp issue at his grandmother's in 1885.The 3 Skilling Banco was unsually yellow in color but the boy, nevertheless, took the stamp to a dealer - Heinrich Lichtenstein who was buying copies for 7 Kronor each. The cancellation on the stamp reads Nya Kopparberget posted on July 13, 1857. The error possibly happened because of the insertion of a 3 sklling head when the printing of the 8 skilling yellow stamps were on.Possibly only one or at the most a sheet might have been printed before the printers realised their error and changed the head. Later the stamp changed many hands from Philipp la Rénotière von Ferrary to King Carol of Romania and in 1996 the 'Tre Skilling Banco' as its famously known was sold for a record 2.3 million USD to a swedish dealer named Hans Lernestal. 1857 - British Guiana 1c Magenta The British Guiana magenta varieties were produced by Baum & Dallas, printers based in Georgetown as emergency provisional supplies.The stamps were 4 cent values bering the image of a sailing ship in black on magenta colored paper.In 1875 Vernon Vaughan,a schoolboy, discovered a provisional which was 1c in value instead of the usual 4c's.He then sold it to one, Mr. McKinnon to raise money for other stamps.In the course of time collectors began to believe that there is only one copy of the stamp as no other samples surfaced.Thus began a race between some of the most faous collectors to own the only known copy of the 1c magenta British Guiana.The last known owner of this unique and very collectable stamp is Mr. John Du Pont who brought it for 935,000 $ in 1980. However recently another 1c Magenta has surfaced, owned by Peter Winter's son.There is debate on the authenticity of the stamp which experts are still verifying. 1851 - Hawaiian Missionary Stamps The year 1851 saw Hawaii issue its first set of stamps for the various missionaries involved in religious work, on the islands, to send mail to continental US.The stamps came to be famously called as 'The Hawaiian Missionary stamps' and they were printed in demoninations of 2,5 and 13 cents.The initial ones were printed very crudely on fragile paper, as a result of which only few have survived. The 2 c shown above, is perhaps the rarest of the lot with only 16 copies in exsitence. Mint varieties sell at 750,000 $ while used ones command around 225,000 $.   1847 - Mauritius Post office error In 1847, Mauritius, a British colony located in the Indian Ocean issued its first postal stamps.The governor awarded the contract to print stamps of 1 penny and 2 penny denomination to a watchmaker based in Port Louis.During the printing process the watchmaker engraved the words 'Post Office' instead of 'Post Paid' on some of the stamps.By the time the error was discovered more than 200 copies had been sold. Currently there are less than 30 known copies of these stamps and are valued at around 600,000 $ each depending upon the condition of the stamp. The Mauritius Post Office error touched a new record for the highest price paid for any philatelic item when a cover bearing two of the stamps sold for a mind blowing 3.8 million $. 1867 - USA Franklin Z - Grill The Franklin Z grill is the rarest of the U.S. Stamps as only two copies are known to exist.The Z Grill got its name from a unique pattern which was made up of tiny squares embossed on the stamp.The 'Z - Grill' was devised so that the tiny squares could absorb the cancellation ink once it dried and not let anyone wash the ink off in a bid to reuse the stamp. The Franklin Z-Grill bears the image of Benjamin Franklin and is 1 c in value. But in this particular case, tiny values sell for big money and in 1988, a copy was sold for 930000 $. The other one was traded by Donald Sundman for the Inverted Jenny,another of the remarkable U.S rarities.