I have a box of metallics. Watercolour pans from the hobby store Panduro, and pencisl from Derwent that came in a ScrawlrBox.
The watercolors are mica powders bound by gum arabic. When I have tested other types of metallics, the golden ones (mica based) are usually lightfast, but the ones with purple or reddish hues tend to be fugitive.

I will update this post with after the the swatches have been exposed to light for some months.