A grey holo?

Sally Hansen - Hard as Nails - Xtreme wear - 25 Night Lights

It may be not a grey holo, but it looks like one in artificial light, i guess.

In daylight too, but it was difficult to catch it on camera.

In general, very nice polish.

However, it's a bit difficult to remove, cause it contains glitter.

What's more, you need to apply 3-4 coats to achieve the effect in the photos.

But it dries fast, so it's not a problem.