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难能可贵的人（或物）；令人非常惬意的人（或事物）；精品
If you describe something or someone as a gem, you mean that they are especially pleasing, good, or helpful.
例句
...a gem of a hotel, Castel Clara...
卡斯特尔·克拉拉酒店，酒店中的明珠
Miss Famous, as she was called, was a gem.
“知名小姐”人如其名，是个尤物。