There was an article in Scale Auto a few years ago about these dry pearls, basically they said they can be mixed into anything, lacquer, enamel, acrylic. They can be mixed into clear to be used as a metallic paint, or with less pearl in the mix they are used as a tinted pearl clear for various effects.
I have a few jars to use but did not experiment with them yet (but the colors are very nice, and the flakes look in scale)