Part of the work of developing nail polishes is testing the glitter. Here are a few examples of things that can go wrong.
Curling (these are .062" hexes):
I'm not sure quite what to call this, it's like pitting. These were originally irridescent pink
More curling, except these are square, and they are surprisingly very tiny.
Most of these failed right away, with the exception of the pink hexes which took over a month before they showed any sign of curling.