Part three of the Natalee Grace collection of used US stamps will see a remarkable example of the 4c 1908 imperforate sell with a $50,000 estimate.

The stamp features the Schermack Type III perforations

The stamp is one of the finest examples in existence and, according to the auction house's census - which incorporates the records of the Philatelic Foundation, the Levi Records and its own sales history - is one of just 31 used singles. Overall, 39 used examples exist, with a used strip of three and three covers (one of which bears a strip of three) making up the total.

Aside from its rarity, the stamp also features a fascinating addition - privately added vending machine perforations.

At the beginning of the 20th century, stamp vending and affixing machines were growing in popularity and the Bureau of Engraving and Printing frequently received requests for supplies of imperforate stamps. These imperforates could then by privately perforated to match each firm's machines.

25 sheets (each consisting of 400 stamps) of the 4c issue were delivered to the Schermack Mailing Machine Company in Detroit and cut into coils with the square Schermack Type III perforations. These stamps were then delivered to the Winfield Printing Company for use on mass advertising mailings.

The example at auction boasts large margins with full Schermack performations and neat strikes of the duplex date stamp and oval grid cancel. It provides a fantastic opportunity to invest in one of the finest 4c Grant imperforates on the current market.

Part three of the Natalee Grace collection will sell on September 20 in New York. Part two, which will star a spectacular used example of the 1869 30c invert, takes place the previous day.

Paul Fraser Collectibles specialises in stamp collecting and investment. We continue to bring you the latest news from philatelic auctions across the globe as well as offering our own selection of the rarest and finest British stamps.