You can look at its issuing unit and collection certificate. Generally speaking, the formal postal department will be more reliable. Moreover, pure silver products generally have appraisal certificates, indicating the purity and weight of silver inside. If it has the words and face value of the People's Bank of China on it, it is usually real silver coins, otherwise it is a silver medal. But I want to remind you that even if it is pure silver, the price of this souvenir is definitely more expensive than that of pure silver with the same weight, because they are given as craft gifts.