At the end of this content is the download button of the material but before explain how it has been done.

This is one of the easiest materials of VRay, in a VRayMtl you put the reflections and refractions completely in white color (255.255.255) and the IOR of the refraction to 1.52. If you want to increase the reflections you can increase the IOR of the reflection

To have double reflection and give more realism to the material you must activate the box “Reflect on back side”