Among its many valuable qualities, gold is highly reflective. In fact, so effective are its reflective qualities, that Air Force One, the President’s plane, is equipped with gold-plated reflectors to confuse in-coming heat seeking missiles. Not only that, but astronauts’ visors are coated with a gold film to protect their eyes from the extremely intense rays of the sun they encounter while in space. This speaks of the near perfect reflective quality of highly refined gold.
The reflective qualities of highly refined gold provides a picture of what happens in the heart of the person who is refined by God. In the refining process, God removes the sin, or dross, allowing a more perfect reflection of His image. In this way gold speaks of purity, of holiness, and of the capacity to reflect the image of God.
"The crucible for silver and the furnace for gold, but the LORD tests the heart" (Proverbs 17:3).
The City of God will be "of pure gold, as pure as glass" (Revelation 21:18).