A GOOD FEEDBACK is very important to us. Eagle with snake on cactus. Radiant cap with rays, Denomination. Purity of Silver (see comments). Casa de Moneda de México, Mexico, Mexico (1535-date).On reverse it shows the legend "10 Ds. 20 Gs" (10 Dineros 20 Granos); it is a specification of silver fineness used on colonial times. Pure silver was 12 Dineros, and each Dinero was fractioned on 24 Granos, so 10Ds+20Gs= 10/12 + 20/288 = 83.333% + 6.925% = 90.27% = Silver 903. NOTE: many different varieties in mintmarks. 1 = Real de Catorce (Ce).
3 = Culiacan (Ce, Cn). 5 = Estado de Mexico (EoMo). 7 = Guadalupe y Calvo (GC). 8 = Guanajuato (G, Go).10 = Mexico City (Mo). 11 = Oaxaca (O, Oa). 12 = San Luis Potosi (Pi).