I didn't top coat it because... wait for it.... I added a Spectra Flair top coat over it! for those who aren't familiar with Spectra Flair, it's a paint additive used for auto body painting that turns the paint holo. I added two coats of SF which is in a clear bsse, then topped it with a quick dry top coat.
The color changed quite a bit to a more gray/silver blue, but the trade off is the major holo that you get. You can enlarge and see the linear rainbow. I like the SF but I really want it to not dull the color so much because Mali Blue is gorgeous!