Vietnam - Tu Duc (1848-1883) - 7/10 Quan nd. (KM.500; BNF suppl. 503; Schr.339) - Obv: Tu Duc niên tạo / Rev: Thầt mạch - 3.73 g. - VF, the beginning of the melting of this type of ingots is not known, but they first appeared in a distribution at the 8th moon of the 17th year (1864)