Another difficulty with using undifferentiated precious metals for exchange was that some trust or expertise was required to assure people that the metal was pure. The same problem occurred with other commodities that people tried to use for exchange, such as gems or shells; their value was too uncertain.
使用无差别贵金属交易的另一难题是：人们要依赖一定程度的信任或专业知识，才能确定交易金属的纯度。人们用作交易的其它商品，如宝石或贝壳等，也存在同样的问题。交易商品的价值太不固定。