玉石混淆
gyoku.seki.kon.kou

Literally: jewel – stone – mix – mix

Alternately: Good mixed with bad. Valuable things mixed together with worthless things. Wheat and chaff.

Notes: Rare character 淆 may be replaced with 交 without any change in meaning or pronunciation. However, reading either of these as gou is considered an error, despite what one might guess based on normal rules for voicing in compounds.

This compound comes to us from a 17-century-old Chinese text known as the Baopuzi (抱朴子, in Japanese Houbokushi).

But what if you just polished all the rocks?