(LeonardoS I'm referencing 3D not illustrator here) It looks a lot more complicated than it actually is, it's actually fairly simple to reproduce but it does depend on the software being used... you've got a very subtle 'noise' filter applied to the background colour to give the variation and then there's also a 'smoke' (doesn't look like a another noise texture to me) texture applied as a low depth bump map. They might have also used a subtle gloss as well to give the top of the texture bump maps a little shine.as for the texture that might be more difficult to reproduce