Monaco issued this 60c black, plum, and blue stamp to commemorate an international tournament held in Monte Carlo during March, 1967. The stamp (perf 13) was designed by B. Minne and engraved by Monvoisen. Under the patronage of Prince Rainier, the tournament featured ten players including seven grandmasters. The American, Bobby Fischer, placed first, ahead of GMs Smyslov, Geller, Larsen, Matanovic, Gligoric, and Lombardy. The tournament included one IM, Forintos, and two French masters, Mazzoni and Bergrasser. Fischer placed first ahead of Smyslov, Geller, and Larsen.
Four imperforate trial colors (black, green, blue, and maroon) were also issued.
Here are two common first day covers for the issue.
A special postmark (Checkmate 166A) also commemorated the Monte Carlo tournament.