Rendering Transparent Layer with Shadows (Cycles)

Hi,

Hope someone can help.

I am trying to render jewelry in a simple lightbox environment. I have separated the ground plane, metal and stones into three different layers and composite them together.

I would like to have the flexibility of having the shadows on the ground plane separated onto a separate layer so that I can interchange the colors and texture of the ground plane as required.

I cant seem to find a way to do this. Anyone have an idea?

Thanks!

I think you need to render out a shadow pass. That will give you the shadows separately.