I bought a couple of oil-based Sharpies at Michael's recently—the package says they'll write on metal, pottery, wood, rubber, glass, plastic, and more. I chose a two-pack with gold and silver pens and tried one out on this ceramic cup. Nifty! The paint is opaque and shiny and didn't bead up. Now I'm plotting what else needs gold and silverizing. I'm like Midas with markers.