Answer
All types of imitation jewellery for women is permissible. Only pure silver or pure silver plated equivalent to 4.5 Mashas (67.5 grains troy) rings are permissible for men. (Shaami vol.6 pg.359 HM Sa?eed; Dars-e-Tirmidhi vol.3)
and Allah Ta’ala Knows Best
Mufti Ebrahim Desai