Again, I found myself using the H&M polishes.
Show Off is a beautiful mid bright blue with shimmer, it reminds me a lot of the Ocean Breeze colour from Revlon, or Hypnotic Turquoise by Miss Sporty. My bottle's getting old, so I need to think the formula down, but it's still gorgeous.
Metallic Petrol isn't a petrol colour, at least, it isn't to me. It's a denim. A deep, denim blue that's slightly metallic with tiny silver shimmer/glitter. It dries to a slightly satin finish, so a top coat is needed.