Today I've got a comparison for you. I only compared these two because as I was swatching Radium I was trying to think of other polishes in that colour and Kryptonite was the only one in my stash that came even remotely close. You'll see why you can't actually compare these in a second. (Also, Pieces is a brand available at a local clothing store. I know it's also available in Germany, but beyond that I have no idea where you can get it.)
From index to pinkie this is: Illamasqua Radium, Pieces Kryptonite, Illamasqua Radium, Pieces Kryptonite. (Do ignore the dent on my index finger.)
As you can see, Kryptonite is more yellow-toned than Radium and, while Radium is a shimmery creme bordering on frost, Kryptonite is a jelly. At first I was thrilled that it's a jelly, because I adore jellies. I'm willing to slap on that extra coat just for the squishy finish. However, this one takes a lot of coats to become opaque. I can't remember how many I used for this exactly (my notes are somewhat vague and irritated) but I think it was about 5, perhaps more. Honestly, the first three coats looked more yellow than green, not to mention gross and like I'd painted my nails with yellow highlighter. The consistency of the polish was also very...strange? I don't know; I've never used a polish with that sort of consistency before - it's sort of jelly-like. Almost like it's not actually liquid, but rather creamy? Like I said, strange.
Strange consistency aside, application was smooth and easy. Still, 5+ coats vs 2 coats? Even for a jelly, even for a jelly in such an unusual colour, that's a lot.
I don't want to say I prefer Radium, but I do have to say that I'll wear it more often simply because it doesn't take as long to apply as Kryptonite. (You can also read my review of Radium here.)
Have a lovely Tuesday, everyone!