Transparency on disc labels

[just_dont_ask_why]

I've been searching all over the FAQ sections, and I can't find any answers to this: If I upload an image for my disc label in a file type that supports transparency (such as .PNG), will my disc be printed with the silver-shiny in the parts where I had transparency, or will Lulu automatically just print that part as white?

I'd like to be able to print something like a solid background but have the words transparent so they are shiny. Anyone know how this works?

Thanks!
David