Rich! We'd all love to change metal to gold!!
But... I think this is what you mean:
Here's an article that might help you - https://www.scientificamerican.com/article/fact-or-fiction-lead-can-be-turned-into-gold/
Love your question. Merlin tried that. You can't unless you just paint it with a paint made for metal. Rustoleum has about 3-4 different gold looks including a hammered gold.