台湾籍旅美老师今天交给我们的句子是：

Ideally the diamond is flawless if you can't see any of that stuff under ten times the magnification. The higher the clarity the more rare and expensive it is.
理想来说一颗钻石在放大了十倍之后还没看到任何杂质，它就完美无瑕了。钻石的净度越高，数量就会越少，价格也更昂贵。