Proverbs 17:3
A crucible for silver and a furnace for gold, but the LORD is the tester of hearts.

Isaiah 1:25-27
I will turn My hand against you; I will thoroughly purge your dross; I will remove all your impurities. . . .

Malachi 3:3
And He will sit as a refiner and purifier of silver; He will purify the sons of Levi and refine them like gold and silver. Then they will present offerings to the LORD in righteousness.

2 Timothy 2:20, 21
A large house contains not only vessels of gold and silver, but also of wood and clay. Some indeed are for honorable use, but others are for common use. . . .

1 Peter 1:7
so that the authenticity of your faith--more precious than gold, which perishes even though refined by fire--may result in praise, glory, and honor at the revelation of Jesus Christ.