Leonor - from Oakland, CA
The best way to paint your fondant cake gold is to use Wiltons Gold Pearl Dust; you can paint it on wet or dry. Painting it on wet will produce a vibrant gold color. This is done by mixing equal portions of Pearl Dust and Pure Lemon Extract, and applying the color with a clean brush.
If you are just looking for some added gold sparkle, I'd recommend dry dusting. This is simply done by dipping a dry, clean brush in the color dust and applying it directly to your fondant.