I saw that one after I created some diamonds a while ago. I only reallly used a mentar ray dgs material and played with the settings and got the following pic. I created the scene as I saw a animation of some diamonds dropping that someone did in mental ray and wanted to re-create the look of it (I didn't use caustics for the render as I didn't know how at the time). If you want the material settings then give me a shout and i'll post them up. heres the pic