It's OPI Designer Series Magic over Essie Aruba blue. It's metallic and sparkley, and fairly shimmery or maybe glass fleck? It also looks great over a purple base. It's a bit duo-chrome in the bottle but I can't see it on the nail at all. There are a few dupes that I know of for this polish, two being Orly Lunar Eclipse, and Sally Hansen Laser. I have all three, and I like DS Magic the best with Orly a close second. SH Laser is really pretty but is really sheer.
And below is what Essie Aruba Blue looks like on it's own.
Thanks for looking!