model goes invisible after diffuse node is deleted

Hi all,
Im quite new to Blender and found this tutorial on youtube which shows how to make diamonds

my problem is after i placed the pre-made model diamond, and goes to the node editor and deletes the diffuse node… the render window goes totally black and i cannot see the diamond in edit OR object mode, but it is there as i can see it in all other modes…

in the tutorial no diffuse node is used, only 3 glass shaders, 2 add shaders and a material node…

how do i remedy this? any suggestions would be welcome

i figured out my (n00b) mistake myself, i had started the model in cycles… if i instead started it in render no such problem existed (sneaks shameful out the backdoor) :o