MEXICO. 4 Reales, 1748-MoMF. Mexico City Mint. Ferdinand VI (1746-1759). PCGS AU-53 Secure Holder.KM-95; Gil-M-4-21; Yonaka-M4-48; Cal-Type 97#419; Palmer & Almanzar-226. A desirable grade for this relatively rare denomination with design features that are bold and surfaces that are richly toned, displaying some iridescence around the raised surfaces.PCGS AU-53 Secure Holder.