Glass Material

In order to reduce noise (fireflies) in the rendering, glass material doesn't cast any shadow by default. If you want the shadow back just connect the Glass node (the red one) to the Surface socket of the Material Output.
The glass node allows you to change the amount of caustics you desire as well as the index of refraction.

This blend file contains public domain textures from: ambientcg.com, 3dtextures.me and David Gruwier.
It also contains textures created with images from textures.com. These images may not be redistributed.