My 2 nail polishes using one red just using one from marks and spencer the other is dark navy from nails inc called motcomb street both uk brands. It's best with a dark colour

My nails clean and filed

Paint the underside of the nail with the red 2 coats

Paint the front of nail with dark colour I'm using dark navy

Finished nails 2 coats

Clean up any bits that have gone in skin with cotton bud dipped in nail polish remover I know it's a short guide but I love this effect x