This refers to how gold and silver are refined. A metal is refined by heating it to a high temperature so that it melts and the impurities may be removed. See how you translated the very similar phrase in [Proverbs 17:3](../17/03.md). Alternate translation: "A crucible is used to refine silver and a furnace is used to refine gold" (See: [[rc://en/ta/man/jit/figs-explicit]])
This can be stated in active form. Alternate translation: "when one praises a person, they are also testing that person" (See: [[rc://en/ta/man/jit/figs-activepassive]])