In Scripture bronze symbolizes strength, judgement, and captivity. Gold on the other hand represent rarity, purity and God's deity. Using a gold verses bronze shovel reveals, I believe, how precious the lives that we offer up to Him are. They may not be lives that are perfect or free from failure, but a broken, humble heart the Lord will never despise.
You are probably familiar with this Psalm written by King David, the man after God's heart, after his horrific sin of killing Uriah to cover committing adultery with his wife, and which was revealed (see 2 Samuel 11). What David had done was displeasing to the Lord but his sincere repentance wasn't. I believe his repentance was precious to the Lord and the very reason, in the vision, I saw the Lord Jesus come with a golden shovel, not a shovel of strong bronze judgement.
Many Believers today are stuck in their shame, feeling like the Lord despises them because of their sin. Instead of being set free with the truth of Romans 5:8 that "...God demonstrates His own love toward us, in that while we were still sinners, Christ died for us," they are stuck in "the shame of being a sinner" that Christ needed to die for.
Here is the core of the vision: there was no distain or judgement on the Lord's face as He scooped up the ashes. There was a look of joy and pleasure as He scooped up the precious ashes that come from our lives laid upon the altar of sacrifice in sweet surrender to Him.
Beloved, surrounded by all that ashes of our lives there is a burning ember that He will bring into the Holy Place and use to bring a sweet, smelling aroma to God from the altar of incense. Glory to Yahweh in Yahshusa name.