【沙里淘金】〖sh l táo jn〗[obtain gold by washing it from sand and gravel; extract the essential from a large mass of material; get small returns for great efforts; pan gravel for gold]

沙场久战锻精勇，

里手行家谋屈兵。

淘旧铸新糟粕汰，

金睛火眼辨奸忠。

从沙里淘出黄金。比喻好东西不易得。也比喻做事费力大而收效少。也比喻从大量的材料里选择精华。From sand in amoy out gold. Metaphor  good thing, no easy have to. Also metaphor handle affairs laborious large and produce effects less.同：去粗取精、去伪存真。反：泥沙俱下、鱼龙混杂。