I know nothing about nail polish but thats probably a holographic glitter flake like https://www.amazon.com/INM-Northern-Lights-Silver-Hologram/dp/B000PZA1MC/ref=pd_cp_194_4/138-3389342-1547021?_encoding=UTF8&pd_rd_i=B000PZA1MC&pd_rd_r=613c96c5-681c-495b-a78f-f06c9e875d0a&pd_rd_w=t5l9Y&pd_rd_wg=S6VBw&pf_rd_p=0e5324e1-c848-4872-bbd5-5be6baedf80e&pf_rd_r=JEGJZ23EEXGRDWRWB2DH&psc=1&refRID=JEGJZ23EEXGRDWRWB2DH painted on a black nail?