Stars like described were used by "proletarian" (guard, assault etc.) partisan units. In another partisan units were used red stars without hammer and sickle, made of metal or wool, or sometimes hand embroidered. There are some information about that emblems f.e. in polish book from 70's/80's, titled "Emblematy, godła i symbole GL i AL" ("Emblems, signs and symbols of Peoples Guard and Peoples Army") written by K. Satora.
Described stars were probably made in Yugoslavia - for partisan movement, as well, as in USSR - I have seen a few (and got one) soviet-made small (side-cap size) stars, that were made in zink or brass, and red-painted, not enameled.