Symbolism, Imagery, Allegory
Gold was as much a part of biblical society as it is today—a symbol of power, prestige, and taste. But gold isn't always all it's cracked up to be. Sure it's a marker of value—kings wear it, it's nice and shiny—but it can lead down the wrong path.
So even though God "set a crown of fine gold" on the king's head in Psalm 21:3, we're also readily reminded that God's laws are "more to be desired than gold" (19:10). Money can never buy God's favor, and after all, as we're told in Psalm 49, you can't take it with you.
And we can't think about gold without thinking about idols. For the Israelite writer, it's a major slandering of God's power by giving such a worthless item so high a value:
The idols of the nations are silver and gold,
the work of human hands.
They have mouths, but they do not speak;
they have eyes, but they do not see;
they have ears, but they do not hear,
and there is no breath in their mouths.
Those who make them
and all who trust them
shall become like them. (135:15-18)
So there you have it. The Biblical writers acknowledge the power of gold, but they also lament that it is often used for purposes they don't buy into. Looking for more? Check out Psalms 45:9, 52:7, 62:10, and 68:13. Just remember, all that glitters is not gold.