Amethystinus, Adiectiuum, pen. cor. Iuuen.Of an Amethyst.
Lewis and Short: Latin dictionary
ămĕthystĭnus, a, um, adj. [amethystus]. I.Of the color of amethyst: vestes, Mart. 1, 97, 7.—Also absol.: amethystina (sc. vestimenta), Juv. 7, 136.—II.Set or adorned with amethyst: trientes, Mart. 10, 49.