怎么分别纯银，我妈昨天中奖了一个纯银的杯子

昨天我们这金店做活动
抖音抽奖送东西
我妈中了 据宣传杯子内胆是纯银的
我想验证下，求各位大佬解惑[s:a2:那个…]
[img]https://img.nga.178.com/attachments/mon_202007/03/-7Q5-kj9gZ2oT3cSqo-zk.jpg.medium.jpg[/img]
[img]https://img.nga.178.com/attachments/mon_202007/03/-7Q5-fkqXbZ37T3cSqo-zk.jpg.medium.jpg[/img]
[img]https://img.nga.178.com/attachments/mon_202007/03/-7Q5-wktXbZ36T3cSqo-zk.jpg.medium.jpg[/img]
[img]https://img.nga.178.com/attachments/mon_202007/03/-7Q5-4ssrXbZ30T3cSqo-zk.jpg.medium.jpg[/img]
法王补上
杯子是免费白嫖的