The Museo Nacional will mark the second anniversary of U.N. designation of the stone spheres with a new stamp this month.
It was in 2014 that the U. N. Educational, Scientific and Cultural Organization added the stone balls in the Diquís region of southwest Costa Rica to the world heritage list.
The national museum hopes to promote a satellite museum in Palmar Sur and nearby locations where the balls are found as a major tourism destination.
The stamp is being issued by Correos de Costa Rica, and the official unveiling will be June 23. But the museum said that the stamp has been made by a French printer with bits of pulverized rock added to the ink to give the coating a texture.