I've been searching the net high and low to find out how this is done. I've seen pictures where someone has used one colour of fondant, then it looks like another colour was infused right into the first fondant, as a stripe or flower or some other shape, but the two colours remain totally separate and perfect. It's not a marble effect, it's like two colours infused into the fondant. I'd love to know how this is done if anyone can understand what I'm trying to say. Thanks in advance.

Do you have a picture of this effect? It might help with answering to see what it looks like.

Ooops......You know what? Upon closer inspection, I'm thinking that it's probably not fondant at all, but royal icing. Sorry.