The dispute around these Island have been going on for years between the Phillipines & China and even Vietnam. Some interest group printed them.Perhaps the emblem on the top of the stamp can give a clue? Your stamp is a not in the same serie as in the link.
(((Embassy of Coldland)))
It could be Taiwan the origin of these ?. "Coldland" is some comic book world.Also note the emblem in the cancel,it has the same flower shape with the petals.
A bunch of Coldland stamps. American made then ?