Radium is a super unique bright lime green with bluish-green micro shimmer. The shimmer is more apparent in the bottle than on the nails, but it gives the polish a glow on the nails that a creme or jelly finish wouldn't. With the lime green color and glowing finish, Radium almost looks otherworldly. Though it is slightly yellow-based, I imagine Radium would look great on a variety of skintones. As with all Illamasqua polishes, the formula on this one is perfect. The consistency is creamy, has good flow, and provides opacity at two thin coats. Illamasqua polishes don't chip on me for a good 4-5 days, which is incredible considering how rough I am with my nails. A great way to amp up the shimmer in Radium is by layering Illamasqua's Prism (a sheer white with iridescent blue shimmer) over it. If aliens wore nail polish, it would definitely be this combination!

Spring 2011 Toxic Nature showstopper color. Radium is a gorgeous brighter-than-lime green that reflects a little bit of silver in the light. Application is incredibly smooth (as one would expect of Illamasqua polish), and dries to a beautiful sheen. This is definitely the perfect spring/summer color, with just enough yellow it in to make it pop, but enough green to still be attractive (yellow polish looks good on almost no one, and yes I'm generalizing, but it's true!).
My only complaint (and reason for 4 lippies not 5) is that in the bottle this polish looks like it shimmers blue as well...in application it really does not. If it did, this polish would be all the more amazing, but unfortunately there's no blue to be seen. Take it in the sun and you'll see that yes, it retains some silver shimmer, but that's it.
Would definitely buy again. Will be wearing a lot of this shade this year!