This just like my L'Oreal Mascara
This L'Oreal 820 Crystalissime Nail Polish is perfect as a top coat for any nail polish colour (though I think it's looks best on-top of a purple since it has a purple sheen to it!
As you can see, on a bare nail it really doesn't do it justice but you can see how incredibly sheeny and shiny it is!
As I got this ages ago it may be difficult to find this exact one but a similar one is the L'Oreal Paris Color Nail Top Coat - Diamond Lurex this is practically exactly the same except that it has a silver/pearl sheen instead of a purple one, which I think will actually suit more colours.!
You can get it from Boots for £4.99
Have you tried any of the other L'Oreal Top Coats?