The melacha of hotza’ah (carrying) (part 6.5 – abridged)This next application may not be common today, but you never know!
MBY 301:24-28 [Based heavily upon Kitzur Shulchan Aruch: 84:19, “Metsudah” edition, with notes, translated and annotated by Rabbi Avrohom Davis] One who wears an amulet (Heb. ‘kamaiya’) must consult a halachic authority as to whether or not he may go out with it on Shabbos, because not all amulets are of equal value. A woman who wears a stone called sternschuss to prevent miscarriage may go out with it on Shabbos.
(Ed. The issue here is that in order to be considered an “ornament”, a ‘kamaya’ needs to be “certified” by an expert as possessing bona fide healing-powers. I don’t know if there are “licensed Jewish spiritual healers” today who have the ‘mesorah’ (tradition) on writing authentic ‘kamaiyas’, but I suspect there are.)