So I think the necklace has to be understood in terms of the history of how Jesuits worked to convert, particularly non-monotheists. They would slowly absorb the features of the local religion, then slowly integrate them into a hybrid version of Catholicism, This hybrid version would be used to convert the population, with the assumption that the converted would mainstream more over time. The description for the amulet mentions that it is related to 'offering'. As in 'burnt offering' as in sacrifice. So what we have in this amulet is a barely Christianised version of Mesoamerican cannibal/sacrifice trophy. https://en.wikipedia.org/wiki/Human_trophy_taking_in_Mesoamerica
"There are also several figures showing characters with facial skin on their faces: the skin of a flayed human. Urcid’s article in El Sacrificio Humano en la Tradición Religiosa Mesoamericana includes eight illustrations of these trophies in the southern west of Mexico, including a brazier depicting a ball player with a flayed facial mask, wearing a necklace of human bones and carrying a severed head."
If Gloria's necklace is indeed teeth as someone suggested then this represents an inclusion of Mesoamerican sacrifice aspects into 'the cult'. MS-13 also display many Aztec-like symbols, particularly the skull mask that the priests would wear to terrify their victims. -Almost certainly adrenochrome related. Flayed skin mask has been mentioned in regards to 'the video'.