Roman coin antique (275-276 Rome imperatore Tacitus)

Roman coin set in 9k hello gold pendant
RIC 92c, C 100 Antoninianus Obv: IMPCMCLTACITVSAVG - Radiate, draped and cuirassed bust right.
Rev: PROVIDENTIAAVG - Providentia standing left, holding wand over globe and cornucopia. 275-276 (Rome)