All products made out of precious metals are legally certified by INCM - Oporto Assay Office.
The application of assay office marks is only mandatory for silver pieces that weigh more than 2 grams and gold pieces that weigh over 0,5 grams.
You can check the table with legal punches drawings here.
When in doubt all consumers are able to check the veracity of each hallmark at INCM.
Gold and Silver daily quotes available here.