After dividing up my grandmother's jewelry, there were several pins and broaches that no one claimed. This one was left over, and I thought it was kind of cute, but it had a dark spot on the leaf. I figured I could fix it or color over it, so I snagged it and gave it a new home.
I rolled out my craft mat and dug out my alcohol inks. I figured I'd try covering the spot with gold alcohol ink and if that didn't work, I could cover the leaf with a color and no one would notice the dark spot. I dotted some gold ink onto the leaf and smoothed it out as best as I could with a makeup sponge. I noticed that it made the gold finish a little duller/less shiny. So I covered the whole leaf with a thin layer of the gold alcohol ink (a few drops worth) for a uniform look.
I let it dry and the dark spot is completely gone. If you're around a lot of alcohol based liquids, you may want to seal the jewelry with a clear acrylic sealer (or something similar). I left it unsealed and will just have to remember not to put it on until after I have used any hairspray or perfume.