Why is this glass Cycles material casting solid shadows? I created a glass cone with black seams (the seams are a diffuse not transparent material).



When I shine light on it, the cone casts a solid shadow. Why is this? 

I would like to have a (semi) transparent shadow cast from the glass
and a full shadow from the seams.

Here is the link where you can (hopefully) download the blend file:

glass cone
You did have Transparent Shadows disabled in the Material Settings.  Once enabled, you can use the Light Path Node's Is Shadow Ray to Select between the Glass and Transparency shaders to achieve this effect.