Gold is gold -- you can only charge extra for labor, no matter what color it is.
I disagree, I think you would find the price of colloidal gold is relatively expensive. Gold is not always just gold!
I don't understand the problem, first, is he polishing it or not? Usually polishing will remove tarnish on gold.
Second, if he is not polishing it why not paint it?
Third, if he just wants it to look darker (ie not look like gold), why use gold at all?
Paraphrased from my dad's mouth:
Colloidal gold is gold but dissolved in water. It's relatively the same
Paint makes the gold look shiny, which is not the look he is going for.
He almost killed me when I asked him your third question. Gold is a precious metal; he is not selling something like steel, silver, or bronze. I believe most people consider gold and diamonds at the top when buying from a high-quality jewelry store.
My next post will contain a link to a high-quality digital photograph of earrings I have in my hands that have the color/tarnish he wants.