Three-of-a-kind Canadian stamp rarity priced almost $6,000

The 1856 cover bearing a 6p yellow green stamp (Click to enlarge)

This rare 6p yellow green cover, posted from Canada to New York, will sell at Eastern Auctions:- A highly sought-after Canadian rarity will feature in Eastern Auctions' philatelic sale, this weekend (Saturday, June 5).

Dated to 1856, the folded letter sheet (pictured below) was originally mailed from Windsor in Ontario, Canada, to New York.

In its top left-hand corner is a horizontal pair of 1p red brown stamps. The pair has a sheet margin to the right, with clear-to-full margins at its top and bottom.

And to the right of the pair is something even more remarkable: a single 6p yellow green stamp with full-to-large margins all around its edges.

This cover is one of just three known which bears a 6p yellow green, with reported payment of the 3p inland rate to Halifax, Canada, plus the 5p packet rate to the United States.

According to the seller, the stamps are all fresh with a light file fold between the pair and the single which hasn't affected their adhesives.

The three stamps are marked with neat grid cancellations in black, both handstamped in Windsor. A Halifax oval transit stamp can be found on the cover's reverse (reading "JA 28").

The envelope's front also bears a large circular hand stamp, applied in transit, which reads: "Boston Bk. PKT / 5 / FEB 2."

This 8p British Packet single-letter rate cover is described as "unusually clean and highly desirable," and will auction with a Greene Foundation certificate from 1985.

It will appear for sale this Saturday with a pre-auction estimate of CA$6,000 (around US$5,775).