Issued by Luxembourg in 1967, this Caritas charity set features portraits of Prince Henri, Prince Guillaume, and Princess Marie-Astrid during their youth. Each stamp includes a surtax (“+” value) dedicated to charitable welfare programs, a common European philatelic tradition. Printed by Courvoisier S.A., the series is admired for its elegant portrait engraving and soft pastel color palette. The set represents both royal heritage and social welfare themes, making it popular among collectors specializing in royalty, charity issues, and Luxembourg philately. Complete three-stamp sets in fine condition are especially desirable for thematic collections.