Over ChG Emerald Sparkle. My second-favorite combination!
Excuse the frazzle. Over Color Club Uptown Girl.
Aaand my current NOTD: Illudo over Sally Hansen's Green with Envy.
Final notes: Illusion D'or is pretty over cremes, but I like it over particle-d polish: Emerald Sparkle, Groupie, Vampy Varnish. It lends a foil-like texture to the layer under it, which I like. It tends to be somewhat lackluster (as one coat) over cremes. Also, the color has a tendency to lighten and warm up with a coat of Illudo.
I know, I know, I know that I haven't covered well-roundedly a bunch of colors. What about metallics? Duochromes? Blues? straight-up glitter? But do not tempt me. I had to put this polish away so I could stop compulsively layering it over everything I wore. Given time and self-control, more swatches may come up!