What are the most valuable Canadian stamps?

According to Maclean's and The Richest, the most valuable Canadian stamp is the 12d Black Queen Victoria from the year 1851. One in mint condition with full gum is estimated to be worth around 300,000 Canadian dollars as of Sept. 10th, 2013.

Other valuable Canadian stamps include the two-cent Large Queen on laid paper from 1868 valued at $250,000, the eight-cent Registration Sheet of 50 valued at $200,000, the 25-cent London to London Flight valued between $50,000 to $100,000, the 1982 30-cent Christmas Fold-Over valued at $30,000 and the St. Lawrence Seaway Invert of 1959 valued at $16,000 for a stamp in mint condition.