The 1 Onza coin is produced by the Mexico Mint. It is a 925 sterling silver coin with a weight of 33.625 grams. The actual silver weight is 31.103 grams or 1 oz of pure 999 silver.
33.625 x .925 = 31.103 grams of fine 999 silver
Obverse Lettering: CASA DE MONEDA DE MEXICO
Reverse Lettering:
UNA ONZA DE PLATA PURA<
LEY
925
PESO
33.625
GRAMOS
Mo